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returning primary key after update
Posted on 2013-01-04
I use this appended to an INSERT statement (using Dim PK as long = Command.ExecuteScalar() ) to return the primary key:
SELECT @@Identity
How do I do the same for an UPDATE? I am geting a NULL back.
SELECT @@Identity
How do I do the same for an UPDATE? I am geting a NULL back.
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2 Comments
Active 2 days ago
First off, read this about @@IDENTITY:
http://msdn.microsoft.com/en-us/library/ms187342.aspx
That value is populated as the value of the last identity value generated by a statement.
An update statement shouldn't be automatically generating new identity values (unless you're somehow playing with the value of the identity column?)
In an update statement you're dealing with an existing row, not a newly generated one.
Select the value of the identity column you're updating from the table after the update - the value will be there, it's not something that's newly generated.
If I have a new table with an identity column and I insert 5 rows, @@IDENTITY should return 5 (assuming I start with 1 and increment by 1).
If I come back later and try to update row #5, I need to know the value of the row I'm updating to somehow identify it. I can select from the table after the update where there is some means of identifying the row (a customer number or PO number or whatnot) and check the value of the identity column as a part of that query.
http://msdn.microsoft.com/en-us/library/ms187342.aspx
That value is populated as the value of the last identity value generated by a statement.
An update statement shouldn't be automatically generating new identity values (unless you're somehow playing with the value of the identity column?)
In an update statement you're dealing with an existing row, not a newly generated one.
Select the value of the identity column you're updating from the table after the update - the value will be there, it's not something that's newly generated.
If I have a new table with an identity column and I insert 5 rows, @@IDENTITY should return 5 (assuming I start with 1 and increment by 1).
If I come back later and try to update row #5, I need to know the value of the row I'm updating to somehow identify it. I can select from the table after the update where there is some means of identifying the row (a customer number or PO number or whatnot) and check the value of the identity column as a part of that query.
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