SQL server : Difference between Function and Stored Procedure?

UDF can be used in the SQL statements anywhere in the WHERE/HAVING/SELECT section where as Stored procedures cannot be.

UDFs that return tables can be treated as another rowset. This can be used in JOINs with other tables.

Inline UDF's can be though of as views that take parameters and can be used in JOINs and other Rowset operations.

SQL server : What is a NOLOCK?

Using the NOLOCK query optimiser hint is generally considered good practice in order to improve concurrency on a busy system. When the NOLOCK hint is included in a SELECT statement, no locks are taken when data is read. The result is a Dirty Read, which means that another process could be updating the data at the exact time you are reading it. There are no guarantees that your query will retrieve the most recent data. The advantage to performance is that your reading of data will not block updates from taking place, and updates will not block your reading of data. SELECT statements take Shared (Read) locks. This means that multiple SELECT statements are allowed simultaneous access, but other processes are blocked from modifying the data. The updates will queue until all the reads have completed, and reads requested after the update will wait for the updates to complete. The result to your system is delay(blocking).

SQL Server : How to 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.

SQL Server : What are different type of Collation Sensitivity?

Case sensitivity

A and a, B and b, etc.

 

Accent sensitivity

a and á, o and ó, etc.

 

Kana Sensitivity

When Japanese kana characters Hiragana and Katakana are treated differently, it is called Kana sensitive.

 

Width sensitivity

When a single-byte character (half-width) and the same character when represented as a double-byte character (full-width) are treated differently then it is width sensitive.

 

SQL server : What are the different index configurations a table can have?

A table can have one of the following index configurations:

• No indexes
• A clustered index
• A clustered index and many nonclustered indexes
• A nonclustered index
• Many nonclustered indexes

SQL Server : What are the difference between clustered and a non-clustered index?

A clustered index is a special type of index that reorders the way records in the table are physically stored. Therefore table can have only one clustered index. The leaf nodes of a clustered index contain the data pages.

SQL server : 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.

SQL Server : 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.

SQL Server : 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.

Database : What are the authentication modes in SQL Server?

Windows mode and mixed mode (SQL & Windows).

Database : How do you troubleshoot SQL Server if it’s 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

Database : Can you explain the role of each SQL Server 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

Database : What are the OS services that the SQL Server installation adds?

MS SQL SERVER SERVICE, SQL AGENT SERVICE, DTC (Distribution transac co-ordinator)

Database : Which stored procedure will you are running to add a linked server?

sp_addlinkedserver, sp_addlinkedsrvlogin

Database : 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.

Database : 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..

Database : What is a Join in SQL Server?

Join actually puts data from two or more tables into a single result set.

Database : 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.

Database : 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.

Database : What command do we use to rename a db?

sp_renamedb 'oldname' , 'newname'

Well 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.