SQL SERVER Interview Questions-part8

1. What is BCP? When do we use it?
   BulkCopy is a tool used to copy huge amount of data from tables and views. But it won’t copy the structures of the same.
2. What should we do to copy the tables, schema and views from one SQL Server to another?
   We have to write some DTS packages for it. 

SQLSERVER Interview Questions-part7

1. Can you link only other SQL Servers or any database servers such as Oracle?
   We can link any server provided we have the OLE-DB provider from Microsoft to allow a link. For Oracle we have a OLE-DB provider for oracle that microsoft provides to add it as a linked server to the sql server group.
2. Which stored procedure will you be running to add a linked server?
   sp_addlinkedserver, sp_addlinkedsrvlogin
3. What are the OS services that the SQL Server installation adds?
   MS SQL SERVER SERVICE, SQL AGENT SERVICE, DTC (Distribution transac co-ordinator)
4. Can you explain the role of each service?
   SQL SERVER - is for running the databases SQL AGENT - is for automation such as Jobs, DB Maintanance, Backups DTC - Is for linking and connecting to other SQL Servers
5. How do you troubleshoot SQL Server if its running very slow?
   First check the processor and memory usage to see that processor is not above 80% utilization and memory not above 40-45% utilization then check the disk utilization using Performance Monitor, Secondly, use SQL Profiler to check for the users and current SQL activities and jobs running which might be a problem. Third would be to run UPDATE_STATISTICS command to update the indexes
6. Due to N/W or Security issues client is not able to connect to server or vice versa. How do you troubleshoot?
   First I will look to ensure that port settings are proper on server and client Network utility for connections. ODBC is properly configured at client end for connection; Makepipe & readpipe are utilities to check for connection. Makepipe is run on Server and readpipe on client to check for any connection issues.
7. What are the authentication modes in SQL Server?
   Windows mode and mixed mode (SQL & Windows).
8. Where do you think the users names and passwords will be stored in sql server?
   They get stored in master db in the sysxlogins table.
9. What is log shipping? Can we do logshipping with SQL Server 7.0?
   Logshipping is a new feature of SQL Server 2000. We should have two SQL Server - Enterprise Editions. From Enterprise Manager we can configure the logshipping. In logshipping the transactional log file from one server is automatically updated into the backup database on the other server. If one server fails, the other server will have the same db and we can use this as the DR (disaster recovery) plan.
10. SQL Server crashed and you are rebuilding the databases including the master database what procedure to you follow?
    For restoring the master db we have to stop the SQL Server first and then from command line we can type SQLSERVER Ã?¢â‚¬â€œm which will basically bring it into the maintenance mode after which we can restore the master db. 

SQL SERVER Interview Questions-part6

1. Which TCP/IP port does SQL Server run on?
   SQL Server runs on port 1433 but we can also change it for better security.
2. From where can you change the default port?
   From the Network Utility TCP/IP properties �> Port number.both on client and the server.
3. Can we use Truncate command on a table which is referenced by FOREIGN KEY?
   No. We cannot use Truncate command on a table with Foreign Key because of referential integrity.
4. What is the use of DBCC commands?
   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.
5. What command do we use to rename a db?
   sp_renamedb â€Ë?oldname’ , â€Ë?newname’
6. Sometimes sp_reanmedb may not work you know because if some one is using the db it will not accept this command so what do you think you can do in such cases?
   In such cases we can first bring to db to single user using sp_dboptions and then we can rename that db and then we can rerun the sp_dboptions command to remove the single user mode. 
7. What is the difference between a HAVING CLAUSE and a WHERE CLAUSE?
   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.
8. What do you mean by COLLATION?
   Collation is basically the sort order. There are three types of sort order Dictionary case sensitive, Dictonary - case insensitive and Binary.
9. When do you use SQL Profiler?
   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..
10. What is a Linked Server?
    Linked Servers is a concept in SQL Server by which we can add other SQL Server to a Group and query both the SQL Server dbs using T-SQL Statements. 

SQL SERVER Interview Questions-part5

1. What are triggers?
   Triggers are special kind of stored procedures that get executed automatically when an INSERT, UPDATE or DELETE operation takes place on a table.
2. How many triggers you can have on a table?
   In SQL Server 6.5 you could define only 3 triggers per table, one for INSERT, one for UPDATE and one for DELETE. From SQL Server 7.0 onwards, this restriction is gone, and you could create multiple triggers per each action.
3. How to invoke a trigger on demand?
   In SQL Server 7.0 there's no way to control the order in which the triggers fire. In SQL Server 2000 you could specify which trigger fires first or fires last using sp_settriggerorder Triggers can't be invoked on demand. They get triggered only when an associated action (INSERT, UPDATE, DELETE) happens on the table on which they are defined. 
4. What are the uses of Triggers?
   Triggers are generally used to implement business rules, auditing. Triggers can also be used to extend the referential integrity checks, but wherever possible, use constraints for this purpose, instead of triggers, as constraints are much faster. Till SQL Server 7.0, triggers fire only after the data modification operation happens. So in a way, they are called post triggers. But in SQL Server 2000 you could create pre triggers also. Search SQL Server 2000 books online for INSTEAD OF triggers.
5. What is a self join? Explain it with an example.
   Self join is just like any other join, except that two instances of the same table will be joined in the query. Here is an example: Employees table which contains rows for normal employees as well as managers. So, to find out the managers of all the employees, you need a self join. 
6. What is normalization?
   The Process of organizing relational data into tables is actually referred to as normalization.
7. What is a Stored Procedure?
   Its nothing but a set of T-SQL statements combined to perform a single task of several tasks. Its basically like a Macro so when you invoke the Stored procedure, you actually run a set of statements.
8. Can you give an example of Stored Procedure?
   sp_helpdb , sp_who2, sp_renamedb are a set of system defined stored procedures. We can also have user defined stored procedures which can be called in similar way.
9. What is the basic difference between clustered and a non-clustered index?
   The difference is that, Clustered index is unique for any given table and we can have only one clustered index on a table. The leaf level of a clustered index is the actual data and the data is resorted in case of clustered index. Whereas in case of non-clustered index the leaf level is actually a pointer to the data in rows so we can have as many non-clustered indexes as we can on the db.
10. When do we use the UPDATE_STATISTICS command?
    This command is basically used when we do a large processing of data. If we do a large amount of deletions any modification or Bulk Copy into the tables, we need to basically update the indexes to take these changes into account. UPDATE_STATISTICS updates the indexes on these tables accordingly. 

SQL SERVER Interview Questions-part4

1. What are cursors?
   Cursors allow row-by-row prcessing of the resultsets.
2. Explain different types of cursors.
   Types of cursors:
   Static, Dynamic, Forward-only, Keyset-driven.
3. What are the disadvantages of cursors?
   Disadvantages of cursors:
   Each time you fetch a row from the cursor, it results in a network roundtrip, where as a normal SELECT query makes only one rowundtrip, however large the resultset is. Cursors are also costly because they require more resources and temporary storage (results in more IO operations). Furthere, there are restrictions on the SELECT statements that can be used with some types of cursors.
4. How can you avoid cursors?
   Most of the times, set based operations can be used instead of cursors. Another situation in which developers tend to use cursors: You need to call a stored procedure when a column in a particular row meets certain condition. You don't have to use cursors for this. This can be achieved using WHILE loop, as long as there is a unique key to identify each row.
5. What is a join?
   Joins are used in queries to explain how different tables are related. Joins also let you select data from a table depending upon data from another table.
6. Explain different types of joins.
   Types of joins:
   INNER JOINs, OUTER JOINs, CROSS JOINs. OUTER JOINs are further classified as LEFT OUTER JOINS, RIGHT OUTER JOINS and FULL OUTER JOINS.
7. Can you have a nested transaction?
   Yes, very much.
8. What is an extended stored procedure?
   An extended stored procedure is a function within a DLL (written in a programming language like C, C++ using Open Data Services (ODS) API) that can be called from T-SQL, just the way we call normal stored procedures using the EXEC statement.
9. Can you instantiate a COM object by using T-SQL?
   Yes, you can instantiate a COM (written in languages like VB, VC++) object from T-SQL by using sp_OACreate stored procedure. 
10. What is the system function to get the current user's user id?
    USER_ID(). Some more system functions: USER_NAME(), SYSTEM_USER, SESSION_USER, CURRENT_USER, USER, SUSER_SID(), HOST_NAME(). 

SQLSERVER Interview Questions-part3

1. What is blocking and how would you troubleshoot it?
   Blocking happens when one connection from an application holds a lock and a second connection requires a conflicting lock type. This forces the second connection to wait, blocked on the first.
2. How to restart SQL Server in single user mode?
   SQL Server can be started from command line, using the SQLSERVR.EXE. This EXE has some very important parameters with which a DBA should be familiar with. -m is used for starting SQL Server in single user mode and -f is used to start the SQL Server in minimal confuguration mode.
3. what are the DBCC commands that you commonly use for database maintenance?
   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.
4. What are statistics?
   Statistics determine the selectivity of the indexes. If an indexed column has unique values then the selectivity of that index is more, as opposed to an index with non-unique values. Query optimizer uses these indexes in determining whether to choose an index or not while executing a query.
5. Under what circumstances they go out of date, how do you update statistics?
   Some situations under which you should update statistics:
   1) If there is significant change in the key values in the index
   2) If a large amount of data in an indexed column has been added, changed, or removed (that is, if the distribution of key values has changed), or the table has been truncated using the TRUNCATE TABLE statement and then repopulated
   3) Database is upgraded from a previous version Look up SQL Server books online for the following commands: UPDATE STATISTICS, STATS_DATE, DBCC SHOW_STATISTICS, CREATE STATISTICS, DROP STATISTICS, sp_autostats, sp_createstats, sp_updatestats
6. What are the different ways of moving data/databases between servers and databases in SQL Server?
   BACKUP/RESTORE, dettaching and attaching databases, replication, DTS, BCP, logshipping, INSERT...SELECT, SELECT...INTO, creating INSERT scripts to generate data.
7. Explian different types of BACKUPs avaialabe in SQL Server?
   Full database backup, differential database backup, transaction log backup, filegroup backup.
8. What is database replicaion?                                                                 Replication is the process of copying/moving data between databases on the same or different servers.
9. What are the different types of replication you can set up in SQL Server?
   SQL Server supports the following types of replication scenarios:
   * Snapshot replication
   * Transactional replication (with immediate updating subscribers, with queued updating subscribers)
   * Merge replication \
10. How to determine the service pack currently installed on SQL Server?    The global variable @@Version stores the build number of the sqlservr.exe, which is used to determine the service pack installed. 

SQLSERVER Interview Questions-part2

1. What's the maximum size of a row?
   8060 bytes.
2. What is lock escalation?
   Strong names are required to store shared assemblies in the global assembly cache (GAC). This is because the GAC allows multiple versions of the same assembly to reside on your system simultaneously, so that each application can find and use its own version of your assembly. This helps avoid DLL Hell, where applications that may be compiled to different versions of your assembly could potentially break because they are all forced to use the same version of your assembly. Another reason to use strong names is to make it difficult for hackers to spoof your assembly, in other words, replace or inject your assembly with a virus or malicious code.
3. What's the difference between DELETE TABLE and TRUNCATE TABLE commands?
   DELETE TABLE is a logged operation, so the deletion of each row gets logged in the transaction log, which makes it slow. TRUNCATE TABLE also deletes all the rows in a table, but it won't log the deletion of each row, instead it logs the deallocation of the data pages of the table, which makes it faster. Of course, TRUNCATE TABLE can be rolled back.
4. What are constraints? Explain different types of constraints.
   Constraints enable the RDBMS enforce the integrity of the database automatically, without needing you to create triggers, rule or defaults. Types of constraints: NOT NULL, CHECK, UNIQUE, PRIMARY KEY, FOREIGN KEY 
5. What is an index?
   Indexes in SQL Server are similar to the indexes in books. They help SQL Server retrieve the data quicker.
6. What are the types of indexes?
   Indexes are of two types. Clustered indexes and non-clustered indexes. When you craete a clustered index on a table, all the rows in the table are stored in the order of the clustered index key. So, there can be only one clustered index per table. Non-clustered indexes have their own storage separate from the table data storage. Non-clustered indexes are stored as B-tree structures (so do clustered indexes), with the leaf level nodes having the index key and it's row locater. The row located could be the RID or the Clustered index key, depending up on the absence or presence of clustered index on the table.
7. I create a separate index on each column of a table. what are the advantages and disadvantages of this approach?
   If you create an index on each column of a table, it improves the query performance, as the query optimizer can choose from all the existing indexes to come up with an efficient execution plan. At the same t ime, data modification operations (such as INSERT, UPDATE, DELETE) will become slow, as every time data changes in the table, all the indexes need to be updated. Another disadvantage is that, indexes need disk space, the more indexes you have, more disk space is used.
8. What is RAID and what are different types of RAID configurations?
   RAID stands for Redundant Array of Inexpensive Disks, used to provide fault tolerance to database servers. There are six RAID levels 0 through 5 offering different levels of performance, fault tolerance.
9. What are the steps you will take, if you are tasked with securing an SQL Server?
   Preferring NT authentication, using server, databse and application roles to control access to the data, securing the physical database files using NTFS permissions, using an unguessable SA password, restricting physical access to the SQL Server, renaming the Administrator account on the SQL Server computer, disabling the Guest account, enabling auditing, using multiprotocol encryption, setting up SSL, setting up firewalls, isolating SQL Server from the web server etc.
10. What is a deadlock and what is a live lock? How will you go about resolving deadlocks?
    Deadlock is a situation when two processes, each having a lock on one piece of data, attempt to acquire a lock on the other's piece. Each process would wait indefinitely for the other to release the lock, unless one of the user processes is terminated. SQL Server detects deadlocks and terminates one user's process. A livelock is one, where a request for an exclusive lock is repeatedly denied because a series of overlapping shared locks keeps interfering. SQL Server detects the situation after four denials and refuses further shared locks. A livelock also occurs when read transactions monopolize a table or page, forcing a write transaction to wait indefinitely.

SQL SERVER Interview Questions-part1

1. What is denormalization and when would you go for it?
   As the name indicates, denormalization is the reverse process of normalization. It's the controlled introduction of redundancy in to the database design. It helps improve the query performance as the number of joins could be reduced.
2. How do you implement one-to-one, one-to-many and many-to-many relationships while designing tables?
   One-to-One relationship can be implemented as a single table and rarely as two tables with primary and foreign key relationships. One-to-Many relationships are implemented by splitting the data into two tables with primary key and foreign key relationships. Many-to-Many relationships are implemented using a junction table with the keys from both the tables forming the composite primary key of the junction table.
3. What's the difference between a primary key and a unique key?
   Both primary key and unique enforce uniqueness of the column on which they are defined. But by default primary key creates a clustered index on the column, where are unique creates a nonclustered index by default. Another major difference is that, primary key doesn't allow NULLs, but unique key allows one NULL only.
4. What are user defined datatypes and when you should go for them?
   User defined datatypes let you extend the base SQL Server datatypes by providing a descriptive name, and format to the database. Take for example, in your database, there is a column called ZIP_Code which appears in many tables. In all these tables it should be varchar(6). In this case you could create a user defined datatype called ZIP_Code_Type of varchar(6) and use it across all your tables.
5. What is bit datatype and what's the information that can be stored inside a bit column?
   Bit datatype is used to store boolean information like 1 or 0 (true or false). Untill SQL Server 6.5 bit datatype could hold either a 1 or 0 and there was no support for NULL. But from SQL Server 7.0 onwards, bit datatype can represent a third state, which is NULL.
6. Define candidate key, alternate key, composite key.
   A candidate key is one that can identify each row of a table uniquely. Generally a candidate key becomes the primary key of the table. If the table has more than one candidate key, one of them will become the primary key, and the rest are called alternate keys. A key formed by combining at least two or more columns is called composite key.
7. What are defaults? Is there a column to which a default can't be bound?
   A default is a value that will be used by a column, if no value is supplied to that column while inserting data. IDENTITY columns and timestamp columns can't have defaults bound to them. See CREATE DEFUALT in books online.
8. What is a transaction and what are ACID properties?
   A transaction is a logical unit of work in which, all the steps must be performed or none. ACID stands for Atomicity, Consistency, Isolation, Durability. These are the properties of a transaction. For more information and explanation of these properties, see SQL Server books online or any RDBMS fundamentals text book.
9. Explain different isolation levels An isolation level determines the degree of isolation of data between concurrent transactions.
   The default SQL Server isolation level is Read Committed. Here are the other isolation levels (in the ascending order of isolation): Read Uncommitted, Read Committed, Repeatable Read, Serializable.
10. How does .NET and SQL SERVER thread is work?
    There are two types of threading pre-emptive and Non-preemptive but Sql Server support Non-preemptive and .NET thread model is different. Because Sql have to handle thread in different way for SQLCLR this different thread are known as Tasking of Threads . In this thread there is a switch between SQLCLR and SQL SERVER threads .SQL SERVER uses blocking points for transition to happen between SQLCLR and SQL SERVER threads. 

ASP.NET 2.0 Interview Questions – (Intermediate)

What is XHTML? Are ASP.NET Pages compliant with XHTML?

In simple words, XHTML is a stricter and cleaner version of HTML. XHTML stands for EXtensible Hypertext Markup Language and is a W3C Recommendation.

Yes, ASP.NET 2.0 Pages are XHTML compliant. However the freedom has been given to the user to include the appropriate document type declaration.

More info can be found at http://msdn2.microsoft.com/en-us/library/exc57y7e.aspx

ADO.NET Interview Questions Part-2

What is Ado.NET?

ñ ADO.NET is an object-oriented set of libraries that allows you to interact with data sources. ñ ADO.NET is a set of classes that expose data access services to the .NET programmer. ñ ADO.NET is also a part of the .NET Framework. ñ ADO.NET is used to handle data access.

What are the two fundamental objects in ADO.NET?

There are two fundamental objects in ADO.NET. Datareader - connected architecture and Dataset - disconnected architecture.

What are the data access namespaces in .NET?

The most common data access namespaces : ñ System.Data ñ System.Data.OleDb ñ System.Data.SQLClient ñ System.Data.SQLTypes ñ System.Data.XML

What are major difference between classic ADO and ADO.NET?

In ADO the in-memory representation of data is the recordset.A Recordset object is used to hold a set of records from a database table. In ADO.NET we have dataset.A DataSet is an in memory representation of data loaded from any data source.

what is the use of connection object in ado.net?

The ADO Connection Object is used to create an open connection to a data source. Through this connection, you can access and manipulate a database.

What are the benefits of ADO.NET?

ñ Scalability ñ Data Source Independence ñ Interoperability ñ Strongly Typed Fields ñ Performance

What is a Clustered Index?

The data rows are stored in order based on the clustered index key. Data stored is in a sequence of the index. In a clustered index, the physical order of the rows in the table is the same as the logical (indexed) order of the key values. A table can contain only one clustered index. A clustered index usually provides faster access to data than does a non-clustered index.

What is a Non-Clustered Index?

The data rows are not stored in any particular order, and there is no particular order to the sequence of the data pages. In a clustered index, the physical order of the rows in the table is not same as the logical (indexed) order of the key values.

Whate are different types of Commands available with DataAdapter ?

The SqlDataAdapter has ñ SelectCommand ñ InsertCommand ñ DeleteCommand ñ UpdateCommand

What is the difference between an ADO.NET Dataset and an ADO Recordset?

ñ Dataset can fetch source data from many tables at a time, for Recordset you can achieve the same only using the SQL joins. ñ A DataSet can represent an entire relational database in memory, complete with tables, relations, and views, A Recordset can not. ñ A DataSet is designed to work without any continues connection to the original data source; Recordset maintains continues connection with the original data source. ñ DataSets have no current record pointer, you can use For Each loops to move through the data. Recordsets have pointers to move through them.

Which method do you invoke on the DataAdapter control to load your generated dataset with data?

DataAdapter’ fill () method is used to fill load the data in dataset.

What are the different methods available under sqlcommand class to access the data?

ñ ExecuteReader - Used where one or more records are returned - SELECT Query. ñ ExecuteNonQuery - Used where it affects a state of the table and no data is being queried - INSERT, UPDATE, DELETE, CREATE and SET queries. ñ ExecuteScalar - Used where it returns a single record.

What is a DataSet?

A DataSet is an in memory representation of data loaded from any data source.

What is a DataTable?

A DataTable is a class in .NET Framework and in simple words a DataTable object represents a table from a database.

What is the data provider name to connect to Access database?

Microsoft.Access

Which namespaces are used for data  access?

ñ System.Data ñ System.Data.OleDB ñ System.Data.SQLClient

What is difference between Dataset. clone and Dataset.copy?

Clone: - It only copies structure, does not copy data. Copy: - Copies both structure and data.

What is difference between dataset and datareader?

ñ DataReader provides forward-only and read-only access to data, while the DataSet object can hold more than one table (in other words more than one rowset) from the same data source as well as the relationships between them. ñ Dataset is a disconnected architecture while datareader is connected architecture. ñ Dataset can persist contents while datareader can not persist contents, they are forward only.

What is DataAdapter?

A data adapter represents a set of methods used to perform a two-way data updating mechanism between a disconnected DataTable and the database. It aggregates four commands: select, update, insert and delete command. One adapter can only generate and fill one table in a DataSet.

What is a Command Object?

The ADO Command object is used to execute a single query against a database. The query can perform actions like creating, adding, retrieving, deleting or updating records.

What is basic use of DataView?

“DataView” represents a complete table or can be small section of rows depending on some criteria. It is best used for sorting and finding data with in “datatable”.

What is the use of Connection Object?

The ADO Connection Object is used to create an open connection to a data source. Through this connection, you can access and manipulate a database.

What are the advantage of ADO.Net?

ñ Database Interactions Are Performed Using Data Commands ñ Data Can Be Cached in Datasets ñ Datasets Are Independent of Data Sources ñ Data Is Persisted as XML.

What is a stored procedure?

A stored procedure is a precompiled executable object that contains one or more SQL statements. A stored procedure may be written to accept inputs and return output

What is the difference between OLEDB Provider and SqlClient ?

SQLClient .NET classes are highly optimized for the .net / sqlserver combination and achieve optimal results. The SqlClient data provider is fast. It's faster than the Oracle provider, and faster than accessing database via the OleDb layer.

What is the use of Parameter Object?

In ADO Parameter object provides information about a single parameter used in a stored procedure or query.

What is DataAdapter?

DataSet contains the data from the DataAdapter which is the bridge between the DataSet and Database. DataAdapter provides the way to retrieve and save data between the DataSet and Database. It accomplishes this by means of request to the SQL Commands made against the database.

What does ADO mean?

ADO stands for ActiceX Data Objects.It was introduced few years ago as a solution to accessing data that can be found in various forms, not only over a LAN but over the internet. It replaced the data access technologies RDO(Remote Data Objects) and DAO (Data Access Objects).

Name some ADO.NET Objects?

ñ Connection Object ñ DataReader Object ñ Command Object ñ DataSet Object ñ DataAdapter Object

What is Data Provider?

A set of libraries that is used to communicate with data source. Eg: SQL data provider for SQL, Oracle data provider for Oracle, OLE DB data provider for access, excel or mysql.

What is the DataTableCollection?

An ADO.NET DataSet contains a collection of zero or more tables represented by DataTable objects. The DataTableCollection contains all the DataTable objects in a DataSet.

What are the benefits of ADO.NET?

ADO.NET offers several advantages over previous versions of ADO and over other data access components. These benefits fall into the following categories: ñ Interoperability ñ Maintainability ñ Programmability ñ Performance ñ Scalability

How to creating a SqlConnection Object?

SqlConnection conn = new SqlConnection("Data Source=DatabaseServer;Initial Catalog=Northwind;User ID=YourUserID;Password=YourPassword");

How to creating a SqlCommand Object?

It takes a string parameter that holds the command you want to execute and a reference to a SqlConnection object. SqlCommand cmd = new SqlCommand("select CategoryName from Categories", conn);

How to load multiple tables into dataset?

SqlDataAdapter da = new SqlDataAdapter("Select * from Id; Select * from Salry", mycon); da.Fill(ds); ds.Tables[0].TableName = "Id"; ds.Tables[1].TableName = "Salary";

What is the provider and namespaces being used to access oracle database?

system.data.oledb

What is the difference between SqlCommand and SqlCommandBuilder?

SQLCommand is used to retrieve or update the data from database. SQLCommandBuilder object is used to build & execute SQL (DML) queries like select insert update& delete.

What is the use of SqlCommandBuilder?

SQL CommandBuilder object is used to build & execute SQL (DML) queries like select insert update& delete.

What are managed providers?

A managed provider is analogous to ODBC driver or OLEDB provider. It performs operation of communicating with the database. ADO.NET currently provides two distinct managed providers. The SQL Server managed provider is used with SQL server and is a very efficient way of communicating with SQL Server. OLEDB managed provider is used to communicate with any OLEDB compliant database like Access or Oracle.

How do I delete a row from a DataTable?

ds.Tables("data_table_name").Rows(i).Delete dscmd.update(ds,"data_table_name")

What inside in DataSet?

Inside DataSet much like in Database, there are tables, columns, constraints, relationships, views and so forth.

Explain ADO.Net Architecture?

ADO.NET provides the efficient way to manipulate the database. It contains the following major components. 1. DataSet Object 2. Data Providers : ñ Connection Object ñ Command Object ñ DataReader Object ñ DataAdapter Object.

What is the difference between int and int32?

Both are same. System.Int32 is a .NET class. Int is an alias name for System.Int32.

What is the role of the DataReader class in ADO.NET connections?

It returns a read-only, forward-only rowset from the data source. A DataReader provides fast access when a forward-only sequential read is needed.

What are advantages and disadvantages of Microsoft-provided data provider classes in ADO.NET?

SQLServer.NET data provider is high-speed and robust, but requires SQL Server license purchased from Microsoft. OLE-DB.NET is universal for accessing other sources, like Oracle, DB2, Microsoft Access and Informix. OLE-DB.NET is a .NET layer on top of the OLE layer, so it’s not as fastest and efficient as SqlServer.NET.

What are acid properties?

ñ Atomicity ñ Consistency ñ Isolation ñ Durability

What is DataRowCollection?

Similar to DataTableCollection, to represent each row in each Table we have DataRowCollection.

What is the use of Ado.net connection?

Establishes a connection to a specific data source.

What are basic methods of Dataadapter?

ñ Fill ñ FillSchema ñ Update

What are the various methods provided by the dataset object to generate XML?

ReadXML : Read’s a XML document in to Dataset. GetXML : This is a function which returns the string containing XML document. WriteXML : This writes a XML data to disk.

What is DataSet Object?

Dataset is a disconnected, in-memory representation of data. It can contain multiple data table from different database.

What is difference between Optimistic and Pessimistic locking?

In Pessimistic locking when user wants to update data it locks the record and till then no one can update data. Other user’s can only view the data when there is pessimistic locking In Optimistic locking multiple users can open the same record for updating, thus increase maximum concurrency. Record is only locked when updating the record.

What is Execute Non Query?

The ExecuteNonQuery() is one of the most frequently used method in SqlCommand Object, and is used for executing statements that do not return result sets (ie. statements like insert data , update data etc.).

What providers does Ado.net uses?

The .NET Framework provides mainly three data providers, they are Microsoft SQL Server, OLEDB, ODBC.