The best answers to the question “SQL Server – Best way to get identity of inserted row?” in the category Dev.
What is the best way to get
IDENTITY of inserted row?
I know about
SCOPE_IDENTITY but don’t understand the pros and cons attached to each.
Can someone please explain the differences and when I should be using each?
I believe the safest and most accurate method of retrieving the inserted id would be using the output clause.
for example (taken from the following MSDN article)
USE AdventureWorks2008R2; GO DECLARE @MyTableVar table( NewScrapReasonID smallint, Name varchar(50), ModifiedDate datetime); INSERT Production.ScrapReason OUTPUT INSERTED.ScrapReasonID, INSERTED.Name, INSERTED.ModifiedDate INTO @MyTableVar VALUES (N'Operator error', GETDATE()); --Display the result set of the table variable. SELECT NewScrapReasonID, Name, ModifiedDate FROM @MyTableVar; --Display the result set of the table. SELECT ScrapReasonID, Name, ModifiedDate FROM Production.ScrapReason; GO
@@IDENTITYreturns the last identity value generated for any table in the current session, across all scopes. You need to be careful here, since it’s across scopes. You could get a value from a trigger, instead of your current statement.
SCOPE_IDENTITY()returns the last identity value generated for any table in the current session and the current scope. Generally what you want to use.
IDENT_CURRENT('tableName')returns the last identity value generated for a specific table in any session and any scope. This lets you specify which table you want the value from, in case the two above aren’t quite what you need (very rare). Also, as @Guy Starbuck mentioned, “You could use this if you want to get the current IDENTITY value for a table that you have not inserted a record into.”
OUTPUTclause of the
INSERTstatement will let you access every row that was inserted via that statement. Since it’s scoped to the specific statement, it’s more straightforward than the other functions above. However, it’s a little more verbose (you’ll need to insert into a table variable/temp table and then query that) and it gives results even in an error scenario where the statement is rolled back. That said, if your query uses a parallel execution plan, this is the only guaranteed method for getting the identity (short of turning off parallelism). However, it is executed before triggers and cannot be used to return trigger-generated values.
The best (read: safest) way to get the identity of a newly-inserted row is by using the
create table TableWithIdentity ( IdentityColumnName int identity(1, 1) not null primary key, ... ) -- type of this table's column must match the type of the -- identity column of the table you'll be inserting into declare @IdentityOutput table ( ID int ) insert TableWithIdentity ( ... ) output inserted.IdentityColumnName into @IdentityOutput values ( ... ) select @IdentityValue = (select ID from @IdentityOutput)
I’m saying the same thing as the other guys, so everyone’s correct, I’m just trying to make it more clear.
@@IDENTITY returns the id of the last thing that was inserted by your client’s connection to the database.
Most of the time this works fine, but sometimes a trigger will go and insert a new row that you don’t know about, and you’ll get the ID from this new row, instead of the one you want
SCOPE_IDENTITY() solves this problem. It returns the id of the last thing that you inserted in the SQL code you sent to the database. If triggers go and create extra rows, they won’t cause the wrong value to get returned. Hooray
IDENT_CURRENT returns the last ID that was inserted by anyone. If some other app happens to insert another row at an unforunate time, you’ll get the ID of that row instead of your one.
If you want to play it safe, always use
SCOPE_IDENTITY(). If you stick with
@@IDENTITY and someone decides to add a trigger later on, all your code will break.