when can indexes be used

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SQL-Server-2005

SQL-Server

Hi,
When do we use indexes in sql queries....?

Posted 22-May-12 1:48am

Member 8660975

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4 solutions

Solution 2

Refer this:

http://odetocode.com/code/237.aspx[^]

Posted 22-May-12 1:53am

sravani.v

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Mehdi Gholam 22-May-12 8:01am

5'ed

sravani.v 22-May-12 23:58pm

Thank you Mehdi

Solution 3

In short:
When there are thousands of records in a table, retrieving information will take a long time.
Therefore indexes are created on columns which are accessed frequently, so that the information can be retrieved quickly.

Indexes can be created on a single column or a group of columns.
When a index is created, it first sorts the data and then it assigns a ROWID for each row.

Effective indexes are one of the best ways to improve performance in a database application.

Posted 22-May-12 1:57am

Prasad_Kulkarni

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Member 8660975 22-May-12 8:04am

Thanks for the reply..
which is prefered for fast fecthing of records 'IN' or 'Indexes' ..?

Prasad_Kulkarni 22-May-12 8:07am

You're welcome!
As I answered when you want to access huge data, Indexes are better.

Member 8660975 22-May-12 8:26am

ok thanks again...

Member 8660975 22-May-12 8:30am

actually i need to fetch records of students using their roll no which is primary key. so i need to fetch top 5 records. so now using indexes is better or v can mention the 5 roll numbers in 'IN' clause and fetch records.
Sorry for more questions.

Solution 4

I suggest also reading Clustered and Nonclustered Indexes Described[^]. It's a short description, but gives quite nicely the big picture.

Posted 22-May-12 9:10am

Wendelius

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Mehdi Gholam · Accepted Answer · 2012-05-22T01:51:00

Solution 1

Indexes are used by sql queries and not used in sql queries.

You create indexes when your queries are not performing well.

Posted 22-May-12 1:51am

Mehdi Gholam

Comments

sravani.v 22-May-12 7:53am

My 5!

Mehdi Gholam 22-May-12 8:01am

Thanks

Member 8660975 22-May-12 7:54am

can we use it where in a query 'IN' keyword is used..?

Mehdi Gholam 22-May-12 8:00am

The IN keyword is for specifying values for columns, not indexes.