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Find whether a column is identity or not ...

In one of the newgroup somebody was asking the way to find whether a column is identity or not. I thought I would write my answer there as an article for the benefit of those who have the same doubt.

I know of two ways of finding whether a given column is an identity column or not. Let me try and explain it ...

Sample Table structure:

Create a sample table with an identity column in it.

Create table [order_details]
(
OrderId int identity,
OrderName varchar(10),
UnitPrice int
)

Method 1: [Easiest way]

Select ColumnProperty(Object_id('order_details'), 'OrderId', 'IsIdentity')

Method 2:

For some reasons if you don't want the above method!! then try this one

Declare @colName varchar(100)
Declare @RetColName varchar(100)

Set @colName = 'OrderId' -- Specify the column name for which you want to check

--Status column = 128 means its an identity column
Select @RetColName=[name] from syscolumns where (status & 128) = 128 and id=(select id
from sysobjects where name='order_details')

If @colName = @RetColName
Print 'Its Identity'
Else
Print 'Not an identity column'
Labels:

Comments

Vadivel said…
param, I am afraid you have understood the question wrongly!!

My post is on finding whether a "Given column" is identity or not.

I am not trying to list out all columns which are identity :)
6:45 PM, November 25, 2005
Vadivel said…
That said, your code might not work well in all cases!! Because status is a bit field and it needs to be queried appropriately.

Select
SO.Name as Tablename,
SC.Name as Columnname
From SysColumns SC, SysObjects SO
Where
(SC.Status & 128) = 128 and SO.ID = SC.ID
order by SO.name
9:36 AM, November 26, 2005
Unknown said…
Other method

IF (SELECT COLUMNPROPERTY( OBJECT_ID('table_name'),'column_name','IsIdentity')) IS NOT NULL
Print 'Its Identity'
Else
Print 'Not an identity column'


http://sqlblogcasts.com/blogs/madhivanan
4:53 PM, December 18, 2007
Vadivel said…
@Madhivanan :: What you have mentioned is what already there as method1 in my post :)
5:01 PM, December 19, 2007
Anonymous said…
I believe that comparing with NULL always gives the 'Its Identity' result since COLUMNPROPERTY is a bit field and always gives a NOT NULL result. I tried it with the other two fields and I still got an 'Its Identity'.
This one worked right for me IF (SELECT COLUMNPROPERTY( OBJECT_ID('table_name'),'column_name','IsIdentity')) = 1 :)
4:09 PM, January 29, 2010
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