问题
I have googled this problem one week and no thing useful I think am not using the correct word
I am using SQL Server 2008 with t-sql and my need is to optimise my function when I insert a new row.
I have a table with first column is the key of integer autoincrement type and other columns are just for information
When we do an insert, SQL Server increments the key automatically and I have to do a select max to get the value, so is there a way like a global variable like @@IDENTITY or a function to avoid the begin end transaction and select max
回答1:
Use SCOPE_IDENTITY:
-- do insert
SELECT SCOPE_IDENTITY();
Which will give you:
The last identity value inserted into an identity column in the same scope. A scope is a module: a stored procedure, trigger, function, or batch. Therefore, two statements are in the same scope if they are in the same stored procedure, function, or batch.
回答2:
Just ran the code:
INSERT INTO Persons (FirstName) VALUES ('Joe');
SELECT ID AS LastID FROM Persons WHERE ID = @@Identity;
and it also works!
回答3:
What about this for last auto increment value
SELECT IDENT_CURRENT('tableName')-IDENT_INCR('tableName');
回答4:
If you are using MySQL you get the auto increment ID of the last insert with:
SELECT LAST_INSERT_ID();
See here for full reference.
回答5:
In my case I had to use @@Identity, because I was inserting into a view. It seems that SCOPE_IDENTITY only works for ones you have explicitly created.
See here:
http://blog.sqlauthority.com/2007/03/25/sql-server-identity-vs-scope_identity-vs-ident_current-retrieve-last-inserted-identity-of-record/
@@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.
来源：https://stackoverflow.com/questions/13451070/how-to-get-the-value-of-autoincrement-of-last-row-at-the-insert