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Category: SQL Server
view more software Tips and Tricks
Updated: 01/20/2012 10:01 AM
Author: Shiju Mathews Status: Resolved. |
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There is situations where we need the Identity column value of the last affected row. After an INSERT, SELECT INTO, or bulk copy statement completes, @@IDENTITY contains the last identity value generated by the statement. If the statement did not affect any tables with identity columns, @@IDENTITY returns NULL. If multiple rows are inserted, generating multiple identity values, @@IDENTITY returns the last identity value generated. If the statement fires one or more triggers that perform inserts that generate identity values, calling @@IDENTITY immediately after the statement returns the last identity value generated by the triggers. If a trigger is fired after an insert action on a table that has an identity column, and the trigger inserts into another table that does not have an identity column, @@IDENTITY will return the identity value of the first insert. The @@IDENTITY value does not revert to a previous setting if the INSERT or SELECT INTO statement or bulk copy fails, or if the transaction is rolled back. @@IDENTITY, SCOPE_IDENTITY, and IDENT_CURRENT are similar functions in that they return the last value inserted into the IDENTITY column of a table. @@IDENTITY and SCOPE_IDENTITY will return the last identity value generated in any table in the current session. However, SCOPE_IDENTITY returns the value only within the current scope; @@IDENTITY is not limited to a specific scope. IDENT_CURRENT is not limited by scope and session; it is limited to a specified table. IDENT_CURRENT returns the identity value generated for a specific table in any session and any scope. For more information, see IDENT_CURRENT. The scope of the @@IDENTITY function is the local server on which it is executed. This function cannot be applied to remote or linked servers. To obtain an identity value on a different server, execute a stored procedure on that remote or linked server and have that stored procedure, which is executing in the context of the remote or linked server, gather the identity value and return it to the calling connection on the local server. SELECT @@IDENTITY: It returns the last IDENTITY value produced on a connection, regardless of the table that produced the value, and regardless of the scope of the statement that produced the value. @@IDENTITY will return the last identity value entered into a table in your current session. While @@IDENTITY is limited to the current session, it is not limited to the current scope. If you have a trigger on a table that causes an identity to be created in another table, you will get the identity that was created last, even if it was the trigger that created it. SELECT SCOPE_IDENTITY(): It returns the last IDENTITY value produced on a connection and by a statement in the same scope, regardless of the table that produced the value. 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. In other words, it will return the last identity value that you explicitly created, rather than any identity that was created by a trigger or a user defined function. SELECT IDENT_CURRENT(‘tablename’): It returns the last IDENTITY value produced in a table, regardless of the connection that created the value, and regardless of the scope of the statement that produced the value. IDENT_CURRENT is not limited by scope and session; it is limited to a specified table. IDENT_CURRENT returns the identity value generated for a specific table in any session and any scope. To avoid the potential problems associated with adding a trigger later on, always use SCOPE_IDENTITY() to return the identity of the recently added row in your T SQL Statement or Stored Procedure. |