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 @@IDENTITY vs SCOPE_IDENTITY()

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genius_palli
Starting Member

42 Posts

Posted - 2009-12-10 : 08:31:48
Hello Experts


Could anyone please help me to get a clear idea about

@@IDENTITY and SCOPE_IDENITY().

I know both these return the last inserted identity values and there is something related with the scope. But not able to get a clear idea.

Please suggest.

Regards
genius_palli

rajdaksha
Aged Yak Warrior

595 Posts

Posted - 2009-12-10 : 08:35:07
Hi

@@IDENTITY will return the last identity value entered into a table in your current session.
The @@IDENTITY is limited to the current session, it is not limited to the current scope

SCOPE_IDENTITY(), like @@IDENTITY, will return the last identity value created in the current session. but it will also limit it to your current scope as well

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R...
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Transact Charlie
Master Smack Fu Yak Hacker

3451 Posts

Posted - 2009-12-10 : 09:21:17
To clarity a little (maybe you should consult the documentation for this kind of question?)
quote:

SCOPE_IDENTITY, IDENT_CURRENT, and @@IDENTITY are similar functions because they return values that are inserted into identity columns.

IDENT_CURRENT is not limited by scope and session; it is limited to a specified table. IDENT_CURRENT returns the value generated for a specific table in any session and any scope. For more information, see IDENT_CURRENT (Transact-SQL).

SCOPE_IDENTITY and @@IDENTITY return the last identity values that are generated in any table in the current session. However, SCOPE_IDENTITY returns values inserted only within the current scope; @@IDENTITY is not limited to a specific scope.

For example, there are two tables, T1 and T2, and an INSERT trigger is defined on T1. When a row is inserted to T1, the trigger fires and inserts a row in T2. This scenario illustrates two scopes: the insert on T1, and the insert on T2 by the trigger.

Assuming that both T1 and T2 have identity columns, @@IDENTITY and SCOPE_IDENTITY will return different values at the end of an INSERT statement on T1. @@IDENTITY will return the last identity column value inserted across any scope in the current session. This is the value inserted in T2. SCOPE_IDENTITY() will return the IDENTITY value inserted in T1. This was the last insert that occurred in the same scope. The SCOPE_IDENTITY() function will return the null value if the function is invoked before any INSERT statements into an identity column occur in the scope.

Failed statements and transactions can change the current identity for a table and create gaps in the identity column values. The identity value is never rolled back even though the transaction that tried to insert the value into the table is not committed. For example, if an INSERT statement fails because of an IGNORE_DUP_KEY violation, the current identity value for the table is still incremented.




Charlie
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Msg 3903, Level 16, State 1, Line 1736
The ROLLBACK TRANSACTION request has no corresponding BEGIN TRANSACTION
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X002548
Not Just a Number

15586 Posts

Posted - 2009-12-10 : 10:35:46
short answer: just use scope

It makes for a minty fresh database



Brett

8-)

Hint: Want your questions answered fast? Follow the direction in this link
http://weblogs.sqlteam.com/brettk/archive/2005/05/25/5276.aspx

Add yourself!
http://www.frappr.com/sqlteam



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DonAtWork
Master Smack Fu Yak Hacker

2167 Posts

Posted - 2009-12-10 : 11:37:36
Brett: I now hate you.

http://weblogs.sqlteam.com/jeffs/archive/2008/05/13/question-needed-not-answer.aspx
How to ask: http://weblogs.sqlteam.com/brettk/archive/2005/05/25/5276.aspx

For ultra basic questions, follow these links.
http://www.sql-tutorial.net/
http://www.firstsql.com/tutor.htm
http://www.w3schools.com/sql/default.asp
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X002548
Not Just a Number

15586 Posts

Posted - 2009-12-10 : 17:12:35
quote:
Originally posted by DonAtWork

Brett: I now hate you.



The list is long...

Every use @@IDENTITY for ANY reason?



Brett

8-)

Hint: Want your questions answered fast? Follow the direction in this link
http://weblogs.sqlteam.com/brettk/archive/2005/05/25/5276.aspx

Add yourself!
http://www.frappr.com/sqlteam



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DonAtWork
Master Smack Fu Yak Hacker

2167 Posts

Posted - 2009-12-11 : 07:43:01
I have no qualms about your advise for syntax or function use.

Your abuse of humor is unforgivable, however.

http://weblogs.sqlteam.com/jeffs/archive/2008/05/13/question-needed-not-answer.aspx
How to ask: http://weblogs.sqlteam.com/brettk/archive/2005/05/25/5276.aspx

For ultra basic questions, follow these links.
http://www.sql-tutorial.net/
http://www.firstsql.com/tutor.htm
http://www.w3schools.com/sql/default.asp
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