SQL Server

Question: What is Cascade and Restrict when we use DROP table in SQL SERVER ?
Answer:- When we are using Drop table in SQL the syntax is simple.Drop table table_name(CASCADE / RESTRICT)We use cascade to drop table although it have some dependencies just like triggers, stroeprocrdure, primarykey, foreignkey it will delete first.But if we use restrict a error message is shown on using of DROP if the table have relation Trigger,storeprocedure. 

Question: What is COMMIT & ROLLBACK statement in SQL ?
Answer: Commit statement helps in termination of the current transaction and do all the changes that occur in transaction persistent and this also commits all the changes to the database.COMMIT we can also use in store procedure.ROLLBACK do the same thing just terminate the currenct transaction but one another thing is that the changes made to database are ROLLBACK to the database. 

Question:-What is diffrence between OSQL and Query Analyzer ?
Answer:-Both are the same but ther eis little diffrence OSQL is command line tool whic is execute qery and display the result same a query analyzer but query analyzer is graphical and OSQL is a command line tool.OSQL have not ability like query analyzer to analyze queries and show statics on speed of execution and other usefull thing about OSQL is that its helps in scheduling. 

Question: What is SQL whats its uses and its component ?
Answer: The Structured Query Language (SQL) is foundation for all relational database systems. Most of the large-scale databases use the SQL to define all user and administrator interactions. QL is Non-Procedural language . Its allow the user to concentrate on specifying what data is required rather than concentrating on the how to get it. The DML component of SQL comprises four basic statements:

* SELECT to get rows from tables * UPDATE to update the rows of tables* DELETE to remove rows from tables*
INSERT to add new rows to tables

Question: What is DTS in SQL Server ?
Answer: If a organization is big then it is also there that there is multiple option to store data some people are using EXCEL some are using ACCESS and some of they are using SQL SERVER and in some other format also but there a problem is arise that how to merge that data into one format there is diffrent tool are there for doing this funtion. One of product of SQL SERVER-2000 DTS helps in this problem it provides a set of tool from that tool we can customise are database acording to our need DTSRun is a command-prompt utility used to execute existing DTS packages.

Question: What is the diffrence between SQL and Pl/Sql ?
Answer: We can get modify, Retrieve by single command or statement in SQL but PL/SQL process all SQL statements one at a time. With PL/SQL, an entire block of statements process in a single command line.sql is structured query language ,various queries are used to handle the database in a simplified manner. while pl/sql is procedural language contains various types of variable,functions and procedures and other major diffrence is Sql as the name suggest it is just structured query language wheareas PLSQL is a commbination of Programming language & SQL.

Question: Can You explain integration between SQL Server 2005 and Visual Studio 2005 ?
Answer: This intergration provide wider range of development with the help of CLR for database server.Becasue CLR helps developers to get flexibility for developing database applications and also provides language interoperability just like Visual C++, Visual Basic .Net and Visual C# .Net. The CLR helps developers to get the arrays, classes and exception handling available through programming languages such as Visual C++ or Visual C# which is use in stored procedures, functions and triggers for creating database application dynamically and also provide more efficient reuse of code and faster execution of complex tasks. We particularly liked the error-checking powers of the CLR environment, which reduces run-time errors

Question: What are Checkpoint in SQL Server ?
Answer: When we done operation on SQL SERVER that is not commited directly to the database.All operation must be logged in to Transaction Log files after that they should be done on to the main database.CheckPoint are the point which alert Sql Server to save all the data to main database if no check point is there then log files get full we can use Checkpoint command to commit all data in the SQL SERVER.When we stop the SQL Server it will take long time because Checkpoint is also fired.

Question: What is the difference between UNION ALL Statement and UNION ?
Answer:- The main difference between UNION ALL statement and UNION is UNION All statement is much faster than UNION,the reason behind this is that because UNION ALL statement does not look for duplicate rows, but on the other hand UNION statement does look for duplicate rows, whether or not they exist.

Question: Write some disadvantage of Cursor ?
Answer:- Cursor plays there row quite nicely but although there are some disadvantage of Cursor .Because we know cursor doing roundtrip it will make network line busy and also make time consuming methods. First of all select query gernate output and after that cursor goes one by one so roundtrip happen.Another disadvange of cursor are ther are too costly because they require lot of resources and temporary storage so network is quite busy.

Question: What is Log Shipping and its purpose ?
Answer: In Log Shipping the transactional log file from one server is automatically updated in backup database on the other server and in the case when one server fails the other server will have the same DB and we can use this as the DDR(disaster recovery) plan.

Question: What are the null values in SQL SERVER ?
Answer: Before understand the null values we have some overview about what the value is. Value is the actual data stored in a particular field of particular record. But what is done when there is no values in the field.That value is something like .Nulls present missing information. We can also called null propagation.

Question: What is difference between OSQL and Query Analyzer ?
Answer: Both are same for functioning but there is a little difference OSQL is command line tool which execute query and display the result same a Query Analyzer do but Query Analyzer is graphical.OSQL have not ability like Query Analyzer to analyze queries and show statistics on speed of execution .And other useful thing about OSQL is that its helps in scheduling which is done in Query Analyzer with the help of JOB.

Sql Server 2000 Query

Question: Write a Role of Sql Server 2005 in XML Web Services? Answer:- SQL Server 2005 create a standard method for getting the database engine using SOAP via HTTP. By this method, we can send SOAP/HTTP requests to SQL Server for executing T-SQL batch statements, stored procedures, extended stored procedures, and scalar-valued user-defined functions may be with or without parameters.

Question: What are the different types of Locks ?
Answer: There are three main types of locks that SQL Server
(1)Shared locks are used for operations that does not allow to change or update data, such as a SELECT statement.
(2)Update locks are used when SQL Server intends to modify a page, and later promotes the update page lock to an exclusive page lock before actually making the changes.
(3)Exclusive locks are used for the data modification operations, such as UPDATE, INSERT, or DELETE.

Question: Explain some SQL Server 2000 Query?
Answer: Here are some sql server 2000 query like Sql Insert Query, Delete Sql Query, Update Sql Query and Sql Create Query:
1) Sql Insert Query:
a) How to encrypt data by using
Sql Insert Query.--: insert into table_name(Tablecolumn1, tablecolumn2,. . . . .) values ('value1', pwdencrypt('value'),. . . .)
b) How to copy data from one table to another with the help of
Sql Insert Query.--: insert into table_name(column1,column2,. . . . )
select column1, column2, . . . . from table_name2
c) Sql Insert Query using where clause
--: insert into tablename(column1,column2) select column1,column2 from tablename2 where id=value.

Question: What is 'Write-ahead log' in Sql Server 2000 ?
Answer: Before understanding it we must have an idea about the transaction log files. These files are the files which holds the data for change in database .Now we explain when we are doing some Sql Server 2000 query or any Sql query like Sql insert query,delete sql query,update sql query and change the data in sql server database it cannot change the database directly to table .Sql server extracts the data that is modified by sql server 2000 query or by sql query and places it in memory.Once data is stores in memory user can make changes to that a log file is gernated this log file is gernated in every five mintues of transaction is done. After this sql server writes changes to database with the help of transaction log files. This is called Write-ahead log.

Question: What do u mean by Extents and types of Extends ?
Answer: An Extent is a collection of 8 sequential pages to hold database from becoming fregmented. Fragment means these pages relates to same table of database these also holds in indexing. To avoid for fragmentation Sql Server assign space to table in extents. So that the Sql Server keep upto date data in extents. Because these pages are continously one after another. There are usually two types of extends:-Uniform and Mixed. Uniform means when extent is own by a single object means all collection of 8 ages hold by a single extend is called uniform.Mixed mean when more then one object is comes in extents is known as mixed extents.

Question: What is different in Rules and Constraints ?
Answer: Rules and Constraints are similar in functionality but there is a An little diffrence between them.Rules are used for backward compatibility . One the most exclusive diffrence is that we an bind rules to a datatypes whereas constraints are bound only to columns.So we can create our own datatype with the help of Rules and get the input according to that.

Question: What is defaults in Sql Server and types of Defaults ?
Answer: Defaults are used when a field of columns is allmost common for all the rows for example in employee table all living in delhi that value of this field is common for all the row in the table if we set this field as default the value that is not fill by us automatically fills the value in the field its also work as intellisense means when user inputing d it will automatically fill the delhi . There are two types of defaults object and definations.Object deault:-These defaults are applicable on a particular columns . These are usually deined at the time of table designing.When u set the object default field in column state this column in automatically field when u left this filed blank.Defination default:-When we bind the datatype with default let we named this as dotnet .Then every time we create column and named its datatype as dotnet it will behave the same that we set for dotnet datatype.

Question: What Is Database ?

Answer: A database is similar to a data file in that it is a storage place for data. Like a data file, a database does not present information directly to a user; the user runs an application that accesses data from the database and presents it to the user in an understandable format.Database systems are more powerful than data files in that data is more highly organized. In a well-designed database, there are no duplicate pieces of data that the user or application must update at the same time. Related pieces of data are grouped together in a single structure or record, and relationships can be defined between these structures and records.When working with data files, an application must be coded to work with the specific structure of each data file. In contrast, a database contains a catalog that applications use to determine how data is organized. Generic database applications can use the catalog to present users with data from different databases dynamically, without being tied to a specific data format. A database typically has two main parts: first, the files holding the physical database and second, the database management system (DBMS) software that applications use to access data. The DBMS is responsible for enforcing the database structure, including: · Maintaining relationships between data in the database. Ensuring that data is stored correctly, and that the rules defining data relationships are not violated. · Recovering all data to a point of known consistency in case of system failures.

Question: what is Relational Database ?
Answer: Although there are different ways to organize data in a database, relational databases are one of the most effective. Relational database systems are an application of mathematical set theory to the problem of effectively organizing data. In a relational database, data is collected into tables (called relations in relational theory). A table represents some class of objects that are important to an organization. For example, a company may have a database with a table for employees, another table for customers, and another for stores. Each table is built of columns and rows (called attributes and tuples in relational theory). Each column represents some attribute of the object represented by the table. For example, an Employee table would typically have columns for attributes such as first name, last name, employee ID, department, pay grade, and job title. Each row represents an instance of the object represented by the table. For example, one row in the Employee table represents the employee who has employee ID 12345. When organizing data into tables, you can usually find many different ways to define tables. Relational database theory defines a process called normalization, which ensures that the set of tables you define will organize your data effectively.

Question: What is Data Integrity and it's categories ?
Answer: Enforcing data integrity ensures the quality of the data in the database. For example, if an employee is entered with an employee_id value of 123, the database should not allow another employee to have an ID with the same value. If you have an employee_rating column intended to have values ranging from 1 to 5, the database should not accept a value of 6. If the table has a dept_id column that stores the department number for the employee, the database should allow only values that are valid for the department numbers in the company. 

Two important steps in planning tables are to identify valid values for a column and to decide how to enforce the integrity of the data in the column. Data integrity falls into these categories: 

1. Entity integrity
2. Domain integrity
3. Referential integrity
4. User-defined integrity

Entity Integrity: Entity integrity defines a row as a unique entity for a particular table. Entity integrity enforces the integrity of the identifier column(s) or the primary key of a table (through indexes, UNIQUE constraints, PRIMARY KEY constraints, or IDENTITY properties). Domain Integrity: Domain integrity is the validity of entries for a given column. You can enforce domain integrity by restricting the type (through data types), the format (through CHECK constraints and rules), or the range of possible values (through FOREIGN KEY constraints, CHECK constraints, DEFAULT efinitions, NOT NULL definitions, and rules). Referential Integrity: Referential integrity preserves the defined relationships between tables when records are entered or deleted. In Microsoft® SQL Server™ 2000, referential integrity is based on relationships between foreign keys and primary keys or between foreign keys and unique keys (through FOREIGN KEY and CHECK constraints). Referential integrity ensures that key values are consistent across tables. Such consistency requires that there be no references to nonexistent values and that if a key value changes, all references to it change consistently throughout the database. When you enforce referential integrity, SQL Server prevents users from: · Adding records to a related table if there is no associated record in the primary table. · Changing values in a primary table that result in orphaned records in a related table. · Deleting records from a primary table if there are matching related records. For example, with the sales and titles tables in the pubs database, referential integrity is based on the relationship between the foreign key (title_id) in the sales table and the primary key (title_id) in the titles table. User-Defined: Integrity User-defined integrity allows you to define specific business rules that do not fall into one of the other integrity categories. All of the integrity categories support user-defined integrity (all column- and table-level constraints in CREATE TABLE, stored procedures, and triggers).

Question: SQL Server runs on which TCP/IP port and From where can you change the default port?Answer: SQL Server runs on port 1433 but we can also change it for better security and From the network Utility TCP/IP properties -->Port number.both on client and the server.

Question: What is the use of DBCC commands?
Answer: DBCC stands for database consistency checker. We use these commands to check the consistency of the databases, i.e., maintenance, validation task and status checks.DBCC CHECKDB - Ensures that tables in the db and the indexes are correctly linked.and DBCC CHECKALLOC To check that all pages in a db are correctly allocated. DBCC SQLPERF - It gives report on current usage of transaction log in percentage. DBCC CHECKFILEGROUP - Checks all tables file group for any damage.

Question: What is the difference between a HAVING CLAUSE and a WHERE CLAUSE?
Answer: Having Clause is basically used only with the GROUP BY function in a query. WHERE Clause is applied to each row before they are part of the GROUP BY function in a query.

Question: When do you use SQL Profiler?
Answer: SQL Profiler utility allows us to basically track Connections to the SQL Server and also determine activities such as which SQL Scripts are running, failed jobs etc.

Question: Can you explain the role of each service?
Answer: SQL SERVER - is for running the databases SQL AGENT - is for automation such as Jobs, DB Maintenance, Backups DTC - Is for linking and connecting to other SQL Servers.

Question: What is Normalization ?
Answer: The logical design of the database, including the tables and the relationships between them, is the core of an optimized relational database. A good logical database design can lay the foundation for optimal database and application performance. A poor logical database design can impair the performance of the entire system.Normalizing a logical database design involves using formal methods to separate the data into multiple, related tables. A greater number of narrow tables (with fewer columns) is characteristic of a normalized database. A few wide tables (with more columns) is characteristic of an nonnomalized database. Reasonable normalization often improves performance. When useful indexes are available, the Microsoft® SQL Server™ 2000 query optimizer is efficient at selecting rapid, efficient joins between tables.Some of the benefits of normalization include: ·Faster sorting and index creation.·A larger number of clustered indexes. For more information, Narrower and more compact indexes.·Fewer indexes per table, which improves the performance of INSERT, UPDATE, and DELETE statements.·Fewer null values and less opportunity for inconsistency, which increase database compactness. As normalization increases, so do the number and complexity of joins required to retrieve data. Too many complex relational joins between too many tables can hinder performance. Reasonable normalization often includes few regularly executed queries that use joins involving more than four tables.Sometimes the logical database design is already fixed and total redesign is not feasible. Even then, however, it might be possible to normalize a large table selectively into several smaller tables. If the database is accessed through stored procedures, this schema change could take place without affecting applications. If not, it might be possible to create a view that hides the schema change from the applications.

Question: Can you explain what View is in SQL ?
Answer: View is just a virtual table nothing else which is based or we can say devlop with SQL SELECT query.So we can say that its a real database table (it has columns and rows just like a regular table),but one difference is that real tables store data,but views can’t. View data is generated dynamically when the view is referenced.And view can also references one or more existing database tables or other views. We can say that it is filter of database.

Question: How to get which Process is Blocked in SQL SERVER ?

Answer:- There are two ways to get this sp_who and sp_who2 . You cannot get any detail about the sp_who2 but its provide more information then the sp_who . And other option from which we can find which process is blocked by other process is by using Enterprise Manager or Management Studio, these two commands work much faster and more efficiently than these GUI-based front-ends.

Question: Can you tell me the difference between DELETE &TRUNCATE commands?
Answer: Delete command removes the rows from a table based on the condition that we provide with a WHERE clause. Truncate will actually remove all the rows from a table and there will be no data in the table after we run the truncate command.

DOT NET REMOTING

Question:-What is Serialization Formatters in .NET Remoting ?

Answer: When any object is to be sent across the transport channel, it must be serialized and packed into a data format that can be transmitted with the wire. On the other end of the wire, this serialized data is read and deserialized back to the actual object. This Serialization is done by message-serialization formatters which convert the field or object's state into a format that is helpful for storage or transmission. Dot Net framework provides us two message-serialization formatters one of them is a binary serialization formatter which converts an object's state into a binary stream and other is SOAP serialization formatter which converts it into an XML string representation that's human readable. The binary serialization formatter much slightly faster.

Question:-What is .NET Remoting ?

Answer: .NET Remoting is an enabler for application communication. It is a generic system for different applications to use to communicate with one another. .NET objects are exposed to remote processes, thus allowing interprocess communication. The applications can be located on the same computer, different computers on the same network, or even computers across separate networks.

Question:- .NET Remoting versus Distributed COM ?

Answer: In the past interprocess communication between applications was handled through Distributed COM, or DCOM. DCOM works well and the performance is adequate when applications exist on computers of similar type on the same network. However, DCOM has its drawbacks in the Internet connected world. DCOM relies on a proprietary binary protocol that not all object models support, which hinders interoperability across platforms. In addition, have you tried to get DCOM to work through a firewall? DCOM wants to communicate over a range of ports that are typically blocked by firewalls. There are a ways to get it to work, but they either decrease the effectiveness of the firewall (why bother to even have the firewall if you open up a ton of ports on it), or require you to get a firewall that allows support for binary traffic over port 80.

Question:- Security in Remoting ?

Answer: Security is of paramount importance to any distributed application. Although the .NET Remoting infrastructure does not define any security features itself, because distributed applications are managed code they have full access to all of the .NET security features. In addition, the HTTP channel, when used with IIS, allows you to take full advantage of the authentication and authorization features that are available to Web based protocols. If you choose to use a protocol other than HTTP with IIS, then you have the opportunity to create your own security infrastructure.

Question:-Advantage of Remoting over Web Services ?

Answer: .NET Remoting is a distributed objects infrastructure. It allows processes to share objects—to call methods on and access properties of objects that are hosted in different application domains within the same process, different processes executing on the same computer, on computers on an intranet, or on computers distributed over wide areas. .NET Remoting supports many different communications protocols, including the SOAP/HTTP protocol used by ASP.NET Web services. Support for other protocols makes it possible to provide much faster communications in .NET Remoting than would be possible with ASP.NET Web services. The ASP.NET programming model is tied specifically to IIS, and is limited to creating Web services that use the producer/consumer model. .NET Remoting, on the other hand, can share objects from any type of application.
The .NET Remoting system, as an integral part of the .NET Framework, supports full .NET type system fidelity. You can pass any object across the wire to a client. This is in contrast to ASP.NET, which is limited to data types that can be expressed with WSDL and XSD.

Question:- Scope of publication ?

Answer: .NET Remoting exposes objects to other application domains as if they are local, with a few exceptions. The two exceptions most likely to trip you up are:• Static members are never remoted. Remoting always deals with some form of object instance member. • Private methods are never remoted. You cannot wrap and pass a delegate to a private method. This includes remote event handlers. The other exceptions are less likely to cause you trouble. The online documentation provides a complete list and explanation of the exceptions.

Question:-What are the Proxies ?

Answer: In the general sense, a proxy is any object that stands in for another, either servicing requests directly or passing the requests on to the object for which it is standing in. In .NET Remoting, the proxy manages the marshaling process and the other tasks required to make cross-boundary calls. The .NET Remoting infrastructure automatically handles creation and management of proxies, although it is possible to create your own proxy classes to plug in to and customize proxy creation, marshaling, and other proxy-related tasks.

Question:-What is Abstract ?

Answer: .NET Remoting provides a powerful and high performance way of working with remote objects. Architecturally, .NET Remote objects are a perfect fit for accessing resources across the network without the overhead posed by SOAP based WebServices. .NET Remoting is easier to use than Java's RMI, but definately more difficult than creating a WebService.

Question:-Some Important Notes

Answer: The dependence on assembly metadata implies that client applications must understand .NET concepts. As a result, applications that make use of .NET Remoting are not interoperable with other systems. Although it's possible to write an XML Web service using .NET Remoting, it's not practical when you consider that ASP.NET is designed specifically for that task. In most cases, in order to use .NET Remoting, both the client and the server must be .NET applications. This makes .NET Remoting a poor choice if you want non-.NET clients to access your service.
Before we get into the nuts and bolts of how Remoting works and how to write programs that take advantage of it, you need to understand some basic Remoting concepts.

Question:-.NET Remoting Overview ?

Answer: .NET Remoting is very flexible. You have a wide range of communications options and activation methods, as well as full control over a distributed object's lifecycle. You can choose TCP or HTTP communications protocols on any port, using text or binary formatting. The .NET Remoting infrastructure supports server activated (single call and singleton) and client activated objects. .NET Remoting gives you many opportunities to "plug in" to the system to customize lifecycle management, marshaling, serialization, messaging, and other services.

XML

Question :Parse an XML file or XML file validation ?
Answer: We can parse an xml FILE with an xsd FILE. It message us that our file is not well-formed and then if it is not valid it lists out the specific reason ,it is quite helpful to find an error in a large XML file it also returns line number which contain error also the tag name. That is done in Visual Studio .NET so to get it to work you will have to change the code around to whatever you want to do. One thing is that we must have namespace in the root element of the XML file.

Question:-Is it possible that XML accept UNICODE characters ?
Answer: Yes XML documents can contain foreign characters, like Norwegian æ ø å , or French ê è é.But XML document can not under stand this to understand this we have to take XML as UNICODE.There are some encoding techniques.
Question:-What is DOM?
Answer: Document Object Model (DOM) is a W3C specification that defines a standard (abstract) programming API to build, navigate and update XML documents. It is a "tree-structure-based" interface. As per the DOM specification, the XML parsers (such as MSXML or Xerces), load the entire XML document into memory, before it can be processed. XPath is used to navigate randomly in the document, and various DOM methods are used to create and update (add elements, delete elements, add/remove attributes, etc.) the XML documents.

Question: What is XMLA define it ?
Answer: First of we take a full form of XMLA (XML Analysis Services). Analysis Service was designed to draw reports from data contained in a Data Warehouses and doesnot have any relation with data structure.From XMLA we can expose the Analysis service data to external world in XML.

Question:-What is XML ?
Answer: XML is the Extensible Markup Language. It improves the functionality of the Web by letting you identify your information in a more accurate, flexible, and adaptable way. It is extensible because it is not a fixed format like HTML (which is a single, predefined markup language). Instead, XML is actually a metalanguage—a language for describing other languages—which lets you design your own markup languages for limitless different types of documents. XML can do this because it's written in SGML, the international standard metalanguage for text document markup (ISO 8879).

Question:-What is XPath?
Answer: XML Path Language (XPath) is a W3C specification that defines syntax for addressing parts of XML document. XML document is considered as a logical tree structure, and syntax based on this consideration is used to address elements and attributes at any level in the XML document. For example, considering the XML document described above in answer to question 2, /abc:Employees/abc:Emp/@EmpID XPath expression can be used to access the EmpID attribute under the (first) Emp element under the Employees document element. XPath is used in various other specifications such as XSLT.

Question:-What is XHTML?
Answer: Is simple words, XHTML, or Extensible HTML, is HTML 4 with XML rules applied to it (each begin tag must have an end tag, attribute values in single/double quotes, etc.). However, the overall vision of XHTML is much more than that. In addition to using XML syntax for HTML, XHTML also encloses specifications such as XHTML Basic (minimal set of modules for devices such as PDAs), XForms (represents the next generation of forms for the Web, and separates presentation, logic, and data), XML Events (provides XML languages with the ability to uniformly integrate event listeners and associated event handlers), etc.

Question:-What is XML Parser ?
Answer: Microsoft's XML parser is a COM component that comes with Internet Explorer 5 and higher. Once you have installed Internet Explorer, the parser is available to scripts.
Microsoft's XML parser supports all the necessary functions to traverse the node tree, access the nodes and their attribute values, insert and delete nodes, and convert the node tree back to XML.

To create an instance of Microsoft's XML parser with JavaScript, use the following code:
var xmlDoc=new ActiveXObject("Microsoft.XMLDOM")

To create an instance of Microsoft's XML parser with VBScript, use the following code:
set xmlDoc=CreateObject("Microsoft.XMLDOM")

To create an instance of Microsoft's XML parser in an ASP page (using VBScript), use the following code:
set xmlDoc=Server.CreateObject("Microsoft.XMLDOM")

The following code loads an existing XML document ("note.xml") into Microsoft's XML parser:

Question:- Some Limitation or Disadvantage of XML?
Answer: XML markup has a few disadvantages:
It can be verbose unless element and attribute names are chosen with care. In large documents the markup overhead need not be large, but in short messages it can be significantly more than the actual data, especially when the element or attribute names are concocted by machine.
Overlapping markup is not permitted (an element cannot start inside one element and end inside another): element markup must nest hierarchically.
Some of the software is truly mediocre.

Question:- How to add in XML document through XSL ?
Answer: XSL (the eXtensible Stylesheet Language) is far more sophisticated than CSS. One way to use XSL is to transform XML into HTML before it is displayed by the browser as demonstrated in these examples:
Below is a fraction of the XML file. The second line,
, links the XML file to the XSL file:
Belgian Waffles
$5.95
two of our famous Belgian Waffles
650
Question:- How do I convert my existing HTML documents into XML?
Answer: Tidy is a command-line utility which runs on a wide variety of operating systems; it uses various command-line switches (parameters) to control its processing. At a minimum, it simply cleans up your HTML by ensuring that elements are properly nested and so on; it also warns you if your HTML uses non-standard code that's likely to cause cross-browser compatibility problems. One of the most useful command-line options is -asxml ("as XML," see?), which does what you seem to be asking. It will properly balance elements, per usual, but it also adds some extra information to the document. For instance, it tacks on an XML declaration, , and a statement, which unambiguously mark this as an XML document. To the root html element it also adds a namespace-declaring attribute that identifies all elements in the document as conforming to the specific XML vocabulary known as XHTML. It even forces all element names to lowercase, since the XHTML standard requires it.

If you're asking about converting HTML to a less generic form of XML than XHTML, your task may turn out to be quite complex. For example, if you've been using HTML to mark up customer invoices, not only the customer's name but also their number, item(s) ordered, quantity, and price are probably all wrapped up inside and tags. How do you know which "kind of paragraph" contains a given kind of information, so you can turn one instance of the p element into a custname element, another into custnumber, another into price, and so on? If you've been using CSS for styling your HTML, you may have supplied the different p elements with class="custname" (etc.) attributes and so on; if that's the case, you may be able to generate meaningful XML using an XSLT stylesheet. There may also be customized software to do the sort of conversion you want. Otherwise you're probably looking down the barrel of an ugly gun.

Question:- What is a schema? What are the limitations of a DTD?
Answer: SCHEMA is nothing but METADATA. The schema holds all the information of the xml file that is to be deployed in the project. Metatdata is nothing about data about data since we know that xml is used for data representation language we will be able to understand what metadata is. Metadata includes the tags that is going to be exchanged to and fro from another xml file. DTD (DATA TYPE DEFINITION ) which supervises two conditions namely well formedness and closeness of the xml file. So the user should be aware of what tags he was put into use of this xml file 'A' should be intimated to another application's XML file 'B', by then our xml file will interact with the another xml file, this is the major limitation and mandatory issue that the developers should follow.

Web Services

Question: Can you define basic element of WebServices and explain any one from them?
Answer: These are as follows SOAP, WSDL and UDDI. And I am explaining about the SOAP(Simple Object Access Protocol) it is a communication protocol it is for communication between application it is platform and language independent.It is based on XML and also help to get from Firwall.

Question: Explain functioning of Web Services Protocols ?
Answer: Http-Get:- This is standard protocol that helps client to communicate with server with HTTP.When client send a request to server via HTTP request and reuired parameter are attached with the querystring.Example:-
http://www.dotnetquestion.info/dotnet/interview.aspx?id=pervej&cast=munjal and we get the value from querystring.
Request.querystring("id")
Request.querystring("cast").

Http-Post:-This is same as Http-Get but the diffrence is that in place of sending parameters onto the URL information is send with HTTP request message with some extra information which contains Parameters and their values.This Protocols is limited to sending name/value pairs.

SOAP:-The only diffrence is that its relies on the XML as compares to Http-Get,Http-Post.SOAP can send not only the name/value pairs but also some complex object also as for example datatypes,class,objects.SOAP can also uses request/reponse model as Http-Get,Http-post but it is not limited to Request/Response it can also send types of message.Because its uses XML that is pure text so firewalls not created so much problem because its easily converted in to HTML.

Question: How .NET and non .NET component communicate with each other when they are on different platform?
Answer: In past when we have to communicate .NET with non .NET component we are using COM component this component helps in doing this. At the moment we are using in both apps a COM component that has an intermediary Windows service running on one machine. But this component is quite old and not in use now because it will create a problem when we are using firewall. So to handle this we use Web-Services which really have a solution for Firewall.

Question: Why do some web service classes derive from System.Web.WebServices while others do not ?
Answer: Those asp net Web Service classes which employ objects like Application, Session, Context, Server, and User have to derive from System.Web.WebServices. If it does not use these objects, it is not necessary to be derived from it.

Question: What is WSDL ?
Answer: WSDL is an XML format for describing network services as a set of endpoints operating on messages containing either document-oriented or procedure-oriented information. The operations and messages are described abstractly, and then bound to a concrete network protocol and message format to define an endpoint. Related concrete endpoints are combined into abstract endpoints (services). (Source: www.w3.org).

Question: What is the standard you use to wrap up a call to a Web service ?
Answer: HTTP with SOAP.

Question: What is Asp Net Web Services ?
Answer: Web services are programmable business logic components that provide access to functionality through the Internet. Standard protocols like HTTP can be used to access them. Web services are based on the Simple Object Access Protocol (SOAP), which is an application of XML. Web services are given the .asmx extension..

Question: Define Protocols that helps Web Services in Asp Net?
Answer: From my point of view Web Services used three protocols for interacting with the clients.Http-Post,Http-Get,SOAP.

Question: What are VSDISCO files ?
Answer: VSDISCO files are DISCO files that enable dynamic discovery of Web Services. ASP.NET links the VSDISCO to a HTTP handler that scans the host directory and subdirectories for ASMX and DISCO files and returns a dynamically generated DISCO document. A client who requests a VSDISCO file gets back what appears to be a static DISCO document.

Question: What is UDDI ?
Answer: UDDI stands for Universal Description, Discovery, and Integration. It is like an "Yellow Pages" for Web Services. It is maintained by Microsoft, IBM, and Ariba, and is designed to provide detailed information regarding registered Web Services for all vendors. The UDDI can be queried for specific Web Services.

Question: Is it possible to generate the source code for an ASP.NET Web service from a WSDL ?
Answer: The Wsdl.exe tool (.NET Framework SDK) can be used to generate source code for an ASP.NET web service with its WSDL link.
Example: wsdl /server http://api.google.com/GoogleSearch.wsdl.

Question: Can you give an example of when it would be appropriate to use a web service as opposed to a non-serviced .NET component ?
Answer: When to Use Asp Net Web Services:
(i)Communicating through a Firewall When building a distributed application with 100s/1000s of users spread over multiple locations, there is always the problem of communicating between client and server because of firewalls and proxy servers. Exposing your middle tier components as Web Services and invoking the directly from a Windows UI is a very valid option.

(ii)Application Integration When integrating applications written in various languages and running on disparate systems. Or even applications running on the same platform that have been written by separate vendors.

(iii)Business-to-Business Integration This is an enabler for B2B intergtation which allows one to expose vital business processes to authorized supplier and customers. An example would be exposing electronic ordering and invoicing, allowing customers to send you purchase orders and suppliers to send you invoices electronically.

(iv)Software Reuse This takes place at multiple levels. Code Reuse at the Source code level or binary componet-based resuse. The limiting factor here is that you can reuse the code but not the data behind it. Webservice overcome this limitation. A scenario could be when you are building an app that aggregates the functionality of serveral other Applicatons. Each of these functions could be performed by individual apps, but there is value in perhaps combining the the multiple apps to present a unifiend view in a Portal or Intranet.

Question: What are Service Oriented Architectures (SOA) ?
Answer: SOA describes an information technology architecture that enables distributed computing environments with many different types of computing platforms and applications. Web services in asp net are one of the technologies that help make SOAs possible. As a concept, SOA has been around since the 1980s, but many early IT technologies failed to achieve the goal of linking different types of applications and systems. By making early investments with .NET, Microsoft has helped provide the building blocks that today are putting many enterprise customers on the path to successfully implementing SOAs. With SOAs, companies can benefit from the unimpeded flow of information that is the hallmark of connected systems.

Question: What is .NET Passport ?
Answer: .NET Passport is a Web-based service that is designed to make signing in to Web sites fast and easy. Passport enables participating sites to authenticate a user with a single set of sign-in credentials, alleviating the need for users to remember numerous passwords and user names.

C#.NET

Question:-Can it is possible that pointer are also in C#?
Answer: Can you believe C# supports pointers but in a limited extent. We all know pointer is variable that only holds the memory address of another type. But pointer are little different in C# these declared to hold the memory address of value types and arrays also pointer types are not tracked by the default garbage collection mechanism. Pointers are not allowed to point to a reference type or even to a structure type which contains a reference type. Pointers only point to unmanaged types which includes all basic data types, enum types, other pointer types and structs which contain only unmanaged .

Question:-What is Generic class how it helps programmer ?
Answer:Generic is new feature included in .NET it is essential in C# .Because today the projects are more complicated as past so programmer badly need touse better reuse and customize their existing component-based software. So get this high level of code reuse in other languages, programmers have a option that option is Generics .By Using Generics, we can create class templates that support any type.

Question:-What is Partial class ?
Answer:Partial class can also be split into two or more classes. We can also say that a class be physically separated into other parts of the class but within the same namespace and also one more important thing the parts must use the partial keyword.And other classes should also have the same access modifier.When compile is done, all the partial classes will be treated as a single class. Let us list some advantages of having partial classes.
• Allows a clean separation of business logic layer and the user interface.
• The UI code can be hidden from the developer.
• Makes the debugging easier..

Question:-explain some of method of System.Array class ?
Answer:-
Clear():-Set ranges of value to empty.
CopyTo():-Copies element source to desinations.
GetLength()-:Display number of element in given array.
GetValue():-Value of given index in array.
Length():-To get length of array.
SetValue():-Sets the value of given index in the array.
Reverse() :-Reverse the element of Array.
Sort():-Sort the element in array.

Question: What is difference between the System.Array.CopyTo() & System.Array.Clone()?
Answer: The Clone() method returns a new array object containing all the elements in the original array. The CopyTo() method copies the elements into another existing array. Both perform a shallow copy. A shallow copy means the contents (each element) contains references to the same object as the elements in the original array. A deep copy (which neither of these methods performs) would create a new instance of each element's object, resulting in a different, yet identacle object.

Question: Is there an equivalent of exit() for quitting a C# .NET application ?
Answer: Yes, you can use System.Environment.Exit(int exitCode) to exit the application or Application.Exit() if it’s a Windows Forms app.

Question: Is there a way to force garbage collection ?
Answer: Yes. Set all references to null and then call System.GC.Collect(). If you need to have some objects destructed, and System.GC.Collect() doesn’t seem to be doing it for you, you can force finalizers to be run by setting all the references to the object to null and then calling System.GC.RunFinalizers().

Question: Is there regular expression (regex) support available to C# developers ?
Answer: Yes, The .NET class libraries provide support for regular expressions. Look at the System.Text.RegularExpressions namespace.

Question: What is the difference between a struct and a class in C# ?
Answer: From language spec: The list of similarities between classes and structs is as follows. Longstructs can implement interfaces and can have the same kinds of members as classes. Structs differ from classes in several important ways; however, structs are value types rather than reference types, and inheritance is not supported for structs. Struct values are stored on the stack or in-line. Careful programmers can sometimes enhance performance through judicious use of structs. For example, the use of a struct rather than a class for a Point can make a large difference in the number of memory allocations performed at runtime. The program below creates and initializes an array of 100 points. With Point implemented as a class, 101 separate objects are instantiated-one for the array and one each for the 100 elements.

Question: Are private class-level variables inherited ?
Answer: Yes, but they are not accessible, so looking at it you can honestly say that they are not inherited. But they are.

DotNet Framework Versions

(1) .NET Framework 1.0 The first release of the .NET Framework.
Was on February 13, 2002. Its helpsfull in Windows 98, NT 4.0, 2000, and XP.


(2).NET Framework 1.1
*New mobile controls are taken in ASP.NET
*Security changes -Code Access Security in ASP.NET applications is done in new ways
*A new Built-in support for ODBC and Oracle databases are comes in existing manner
*Compact framework is taken as new version for small devices *Internet Protocol
version 6 (IPv6) support *Numerous API changes.


(3).NET Framework 2.0
*Numerous API changes extend the limit
*A new hosting API for native applications wishing to host an instance of the .NET runtime. The new API gives a fine grain control on the behavior of the runtime with regards to multithreading, memory allocation, assembly loading and more (detailed reference). It was initially developed to efficiently host the runtime in Microsoft SQL Server, which implements its own scheduler and memory manager *Full 64-bit support for both the x64 and the IA64 hardware platforms
*Language support for Generics built directly into the .NET CLR
*Many additional and improved ASP.NET web controls
*New data controls with declarative data binding
*New personalization features for ASP.NET, such as support for themes, skins and webparts
*.NET Micro Framework - a version of the .NET Framework related to the Smart Personal Objects Technology initiative.

.NET Framework 3.5

*This include new features that’s are in C# 3.0 and VB.NET 9.0

*Also have support for expression trees and lambda method

*Language Integrated Query (LINQ)

*LINQ to Objects

*LINQ to XML

*LINQ to SQL

*Also include new feature in ADO.NET that is paging *ADO.NET synchronization API to synchronize local caches and server side datastores *Peer-to-peer networking stack, including a managed PNRP resolver[17] *Managed wrappers for WMI and Active Directory APIs[18]
*Enhancements to the WCF and WF runtimes that let WCF work with POX and JSON data, as well as expose WF workflows as WCF services.[19]

*Support for HTTP pipelining and syndication feeds.[19] *ASP.NET AJAX is included

.Net Framework 2.0 Advantages
The .Net Framework (version 2.0) includes 51 assemblies.The .Net Framework (version 2.0) includes 18,619 types; 12,909 classes; 401,759 public methods; 93,105 public properties and 30,546 public events.It includes a new feature called Control State. Control state is similar to view state except that is used to preserve only critical information. For example the gridview control uses control state to store the selected row. Even if you disable the viewstate, the gridview control remembers which row is selected.We can precompile an entire ASP.Net application by using the aspnet_compiler.exe command line tool. If you precompile an application, users do not experience the compilation delay resulting from the first page request.

ADO. NET

Question:-How ADO.NET come into existence ?

Answer: DAO (data access model) is the first Data Access Model that is created for local databases which contains built-in Jet engine which overcome with some problem like performance and functionality issues. After this RDO (Remote Data Object) and ADO (Active Data Object) comes in market which basically designed for Client Server applications but soon ADO is more comfort then RDO. ADO a good architecture. ADO contained all the data in a recordset object which creates problems when implemented on the network where firewalls exist. Because ADO was a connected data access, which make connection open until the application is closed. This creates issue like database security and network traffic. Because open database connections use system resources to a maximum extent making the system performance less effective. This helps in developing of ADO.NET.

Question: What is Asynchronous Database Commands ?

Answer:- When we execute any database. Thread that executing the command waits before the command get fully executing before executing any additional code. Thread is blocked for another process. But Asynchronous Database Commands solve this problem when database command is executing the current thread can continue on other process.Thread can execute a no of database command. There are two benefits of using Asynchronous Database Commands.1) Executing Multiple Databse Commands simultaneously improve performance.2) Because ASP.Net framework uses a limited pool service for request. Whenany request for a page is comes its assign a thread to handle the request. If framework is out of thread then job is in gueses we get error 503. But if we are using asynchronous database command then current thread is release back to current thread pool.

Question:-What is Concurrency and its types?

Answer: When two or more people try to update same type of data then Concurrency helps how to handle this situation there are two types of concurrencyPessimistic:-When one user try to change the data with pessimistic concurrency a lock is placed on the data so that another user cannot change that one after one another can change.Optimistic:-In this if two user works on the same data and one change that data first then second user cannot change that same data becasue the which he have using is allready changed so he cannot do the change becasue change apply to another data that is changed by first user.

Question: How to start Outlook,NotePad file in AsP.NET with code ?
Answer: Here is the syntax to open outlook or notepad file in
ASP.NET VB.NET Process.Start("Notepad.exe") Process.Start("msimn.exe");
C#.NET System.Diagnostics.Process.Start("msimn.exe"); System.Diagnostics.Process.Start("Notepad.exe");

Question: How to get result from two table in SqlDataReader ?

Answer: string str="Select * from table1;Select * from table2"; cmd.commandtext=str; dr=cmd.executereader();

Question: What is Ref Cursor in .NET and how it is link with ExecuteReader ?
Answer: Ref cursor play its role when doing with the oracle database these comes in ODP.NET. Ref Cursors are objects that link to Oracle server-side cursors.These Ref Cursor can be converted in oracle datareader with this Ref cursor we can get result with query written to pl/sql and the result can be get in .net.Now the question arise why we use Ref Cursor when we have an option of ExceuteReader reson is simple when we need more query in pl/sql means our work is done in pl/sql then we need this ref cursor for getting result set because doennot have direct connection to that table.Becasue advantage of pl/sql we can take two opertion in one query.

Question: Define tool Manage Statistics in SQL Serevr 2000 query ?

Answer: SQL Server creates internal statistics on the rows in all of our tables that is used by the Query Optimizer to select the optimal execution plan for our query. And Query Optimizer helps in doing this.Soome time when statistics isnot maintains then this is done by tool Manage Statistics.We can add,edit or delete for statistics that is maintained by SQL Server.We can experiment with different sets of statistics and see how it affects the query otimizer execution plans.

Question: Some important instruction regarding ADO.NET connection string ?

Answer: When we are making connection string always use Server's IP address not the DNS name if we use IP address it will reduce the time taken for connection to establish.Becasue server IP address is used to get a default or named instance of Sql Server that ls running. if we are running the cluster we have to use the Virtual SQL Server IP address.

Question: How to get database schema information when connection object is establish in ADO.NET ?
Answer: There is a method that helps in getting schema information that is GetSchema() and this method is called in three different ways first way when we call this method without any parameter its return the metadata(table, view, stored procedure.indexes etc).When method is called by passing metadata collection name and filter criteria returns the items from the collection after applying the filter criteria and last way is when we called by passing a metadata collection name returns information about items found in the specified collection.

Question: Which one is better WebService and Remoting ?

Answer: Both of these have little difference WebService helpfull where the user who is using WebService doesnot have the .NET plateform. On the otherside for remoting we need .Net plateform on the both side so from both of this remoting is faster then webservice.So keep in mind which of these are you using if you have .net plateform or other.

Question:-What is DataGrid wheater its a Server Control or something else ?
Answer:DataGrid is Web server control a powerful tool for displaying information from a data source. we can display editable data in a professional-looking grid by setting only a few properties. The grid has a sophisticated object model that provides you with great flexibility in how you display the data.

Question:-Define different execute methods of ADO.NET command object ?
Answer: ExecuteScalar:- This method returns a single value from the first row and first column of the result get from the execution of SQL query.
ExecuteNonQuery:- This method executes the DML SQL query just like insert, delete or update and then returns the number of rows affected by the action.
ExecuteReader:- This method returns DataReader object which is a forward-only resultset.
ExecuteXMLReader:- This method is available for SQL Server 2000 or later. Upon execution it builds XMLReader object from standard SQL query.

Question:-What DataReader class do in ADO.NET ?
Answer:To get read-only and forward only access to data we use DataReader .the DataReader object reduces the system overhead because one row at a time is taken into memory so it is quite lightweight. To get second object connection is reconnected. We can create a DataReader object by execute Execute readre() method. There are two Data Reader class one is SqlDataReader and other is OleDbDataReader.

Question:-Why is ADO.NET serialization slower than ADO ?
Answer: ADO uses binary serialization while ADO.NET uses text based serialization. Since the text takes more space, it takes longer to write it out.

Question:-Is XML is a component of ADO.NET ?
Answer: The answer of this question is always Yes because XML is an important component of ADO.NET architecture .ADO.NET use XML to store and transfer data.We not have to convert data to XML format.Datasets helps XML to integrate with ADO.NET. XML schema plays a role to get table definition,column,datatypes and constraints helps DataSet.

Question:- How to check if the Dataset has records ?
Answer: if ds.Tables(0).Rows.Count= 0 then 'No record else 'record found

Question:- What is the significance of CommandBehavior.CloseConnection ?
Answer: To avoid having to explicitly close the connection associated with the command used to create either a SqlDataReader or and OleDbDataReader, pass the CommandBehavior.CloseConnection argument to the ExecuteReader method of the Connection.dr= cmd.ExecuteReader(CommandBehavior.CloseConnection); The associated connection will be closed automatically when the Close method of the Datareader is called. This makes it all the more important to always remember to call Close on your datareaders.

Question:-Which method do you invoke on the DataAdapter control to load your generated dataset with data?
Answer: The Fill() method.

Question:-What is Dataset and Diffgram?
Answer: When sending and retrieving a DataSet from an XML Web service, the DiffGram format is implicitly used. Additionally, when loading the contents of a DataSet from XML using the ReadXml method, or when writing the contents of a DataSet in XML using the WriteXml method, you can select that the contents be read or written as a DiffGram. For more information, see Loading a DataSet from XML and Writing a DataSet as XML Data. While the DiffGram format is primarily used by the .NET Framework as a serialization format for the contents of a DataSet, you can also use DiffGrams to modify data in tables in a Microsoft SQL Server™ 2000 database.

Question:-What is typed dataset ?
Answer: A typed dataset is very much similar to a normal dataset. But the only difference is that the sehema is already present for the same. Hence any mismatch in the column will generate compile time errors rather than runtime error as in the case of normal dataset. Also accessing the column value is much easier than the normal dataset as the column definition will be available in the schema.

Question:-How can you provide an alternating color scheme in a Repeater control?

Answer: AlternatingItemTemplate Like the ItemTemplate element, but rendered for every other row (alternating items) in the Repeater control. You can specify a different appearance for the AlternatingItemTemplate element by setting its style properties.

Question:-What are good ADO.NET object(s) to replace the ADO Recordset object?
Answer: There are alot...but the base once are SqlConnection, OleDbConnection, etc...

Question:-Can you explain the difference between an ADO.NET Dataset and an ADO Recordset?

Answer:Valid answers are:
A DataSet can represent an entire relational database in memory, complete with tables, relations, and views.
A DataSet is designed to work without any continuing connection to the original data source.
Data in a DataSet is bulk-loaded, rather than being loaded on demand.
There's no concept of cursor types in a DataSet.
DataSets have no current record pointer You can use For Each loops to move through the data.
You can store many edits in a DataSet, and write them to the original data source in a single operation.
Though the DataSet is universal, other objects in ADO.NET come in different versions for different data sources.

Question:-What are the differences between Datalist DataGrid and datarepeater ?

Answer:DataList

1. Has table appearence by default


2. Has no autoformat option


3. has no default paging & sorting options


4. can define separators between elements using templateDataGrid


5. Has a grid appearence by default


6. has a autoformat option


7. has default paging and sorting


8. has no separator between elementsDataRepeater


9. simple,read-only output, has no built in support for selecting or editing items, has no DEFAULT APPEARENCE, has no default paging.

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OOPS

Question: What Is OOPS ?
Answer: OOPs is an Object Oriented Programming language,which is the extension of Procedure Oriented programming language.OOPS reduce the code of the program because of the extensive feature of Polymorphism. OOPS have many properties such as Data-Hiding,Inheritence,Data Absraction,Data Encapsulation and many moreEverything in the world is an object. The type of the object may vary. In OOPS, we get the power to create objects of our own, as & when required.

Question: what is Class ?
Answer:A group of objects that share a common definition and that therefore share common properties, operations, and behavior. A user-defined type that is defined with the class-key 'class,' 'struct,' or 'union.' Objects of a class type consist of zero or more members and base class objects.Classes can be defined hierarchically, allowing one class to be an expansion of another, and classes can restrict access to their members.

Question: What is Constructor?
Answer:When we create instance of class a special method of that class, called that is constructor. Similarly, when the class is destroyed, the destructor method is called. These are general terms and usually not the actual member names in most object-oriented languages. It is initialized using the keyword New, and is destroyed using the keyword Finalize.

Question: What is Abstract Class ?
Answer:Classes that cannot be instantiated. We cannot create an object from such a class for use in our program. We can use an abstract class as a base class, creating new classes that will inherit from it. Creating an abstract class with a certain minimum required level of functionality gives us a defined starting point from which we can derive non-abstract classes. An abstract class may contain abstract methods & non-abstract methods. When a class is derived from an abstract class, the derived class must implement all the abstract methods declared in the base class. We may use accessibility modifiers in an abstract class.An abstract class can inherit from a non-abstract class. In C++, this concept is known as pure virtual method.

Question: What is ValueType?
Answer:Value Types - Value types are primitive types. Like Int32 maps to System.Int32, double maps to System.double.All value types are stored on stack and all the value types are derived from System.ValueType. All structures and enumerated types that are derived from System.ValueType are created on stack, hence known as ValueType.In value type we create a copy of object and uses there value its not the original one.

Question: What is diff. between abstract class and an interface?
Answer: An abstract class and Interface both have method only but not have body of method.The difference between Abstract class and An Interface is that if u call Ablstract class then u have to call all method of that particular Abstract class but if u call an Interface then it is not necessary that u call all method of that particular interface.Method OverLoading:-Return type, Parameter type, parameter and body of method number may be different.Method Overriding:- Return type, Parameter type, Parameter Number all must be same . Only body of method can change.