SQL Server identity

Create Table Test (ID int identity (1, 1), MC varchar (20 ))

Insert into test (MC) values ('aaaaa ')
Select @ identity, ident_current ('test ')

SQL Server 2000 has three similar functions: scope_identity, ident_current, and @ identity. Both return values inserted into the identity column.

Ident_current returns the last generated id value for any session and specific tables in any scope. Ident_current is not restricted by the scope and session, but by the specified table. Ident_current returns the value generated for a specific table in any session and scope.
@ Identity returns the last generated id value for any table in all scopes of the current session.
Scope_identity returns the last generated id value for the current session and any table in the current scope.

Scope_identity and @ identity return the last id value generated in any table in the current session. However, scope_identity only returns the value inserted into 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 is triggered and a row is inserted to T2. This example illustrates two scopes: insert on T1 and insert on T2 as the trigger result.

Assume that both T1 and T2 have the identity column. @ identity and scope_identity return different values at the end of the insert Statement on T1.

@ Identity returns the value of the last identity column inserted to any scope in the current session. This value is the value inserted in T2.

Scope_identity () returns the identity value inserted in T1, which is the last insert that occurs in the same scope. If the scope_identity () function is called when an insert statement occurs in the scope before the identifiers column, the function returns NULL.

The values returned by ident_current ('t1') and ident_current ('t2') are the last auto-increment values of the two tables.