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IDENTITY COLUMN AT SQL

Posted on 2011-03-17
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Last Modified: 2012-05-11
Hi All,

I create a identity column :

IdNo SmallInt IDENTITY(4,1)

I have some questions about it :

1. What does it mean ? How many number is the max number ?
2. How to call it using criteria ?

Thank you.
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Question by:emi_sastra
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9 Comments
 
LVL 22

Accepted Solution

by:
Kelvin Sparks earned 800 total points
ID: 35154909
It is an autonumbering column - in your case it will start from 4, and add 1 to the last used number. Generally used with int insteadof smallint. Provides a unique numbering of records - often for primary keys.

You don't call it

Kelvin
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Assisted Solution

by:greisch
greisch earned 800 total points
ID: 35154927
0
 
LVL 1

Author Comment

by:emi_sastra
ID: 35154954
Hi All,

What I mean call it means how to select it using query ?

What is the maximum number for Int and SmallInt ?

Thank you.
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LVL 13

Expert Comment

by:Rahul Agarwal
ID: 35154961
It is like this

[IdNo] [smallint] IDENTITY(4,1) NOT NULL,

Means that as kelvin says starts from 4 and add 1 to every time the new record insert in the table, but it cannot take deleted [IdNo] value means say if you have 10 records 1-10 and delete the 10th record and insert new record then the [IdNo] takes the 11 not 10 again.
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LVL 13

Assisted Solution

by:Rahul Agarwal
Rahul Agarwal earned 400 total points
ID: 35154970
Please check the link for all the datatype maximum value:

http://www.sql-server-helper.com/faq/data-types-p01.aspx
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LVL 22

Expert Comment

by:Kelvin Sparks
ID: 35155001
Use it the same as any other field in a query

SELECT IdNo FROM yourtable INNER JOIN anothertable ON youtable.IdNo = anothertable.IDNo1
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LVL 1

Author Comment

by:emi_sastra
ID: 35155010
SELECT * FROM yourtable WHERE IdNo = 10 ?

Thank you.
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LVL 22

Expert Comment

by:Kelvin Sparks
ID: 35155022
Yes
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LVL 1

Author Comment

by:emi_sastra
ID: 35155056
Hi All,

Thank you very much for your help.
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