CODEWITHSUNDEEP
sqlsql-server
user8097616
user8097616

Reputation:

SQL Server statement explain

Please explain what the following statements mean. It's an assignment of local variables but I do not understand what inserted or deleted means?

select @ID = ID from inserted 

select @co_ID = co_ID from deleted

Thank you

Upvotes: 0

Views: 91

Answers (2)

Matt Bowler
Matt Bowler

Reputation: 191

INSERTED and DELETED are temporary, memory resident tables created by SQL Server for use (or misuse) within a DML trigger.

Inserts and updates copy new rows into INSERTED, Deletes and updates copy old rows into DELETED.

It looks like this code is attempting to audit a change to a row of data - but will fail unless there is something else in the code path guaranteeing that only a single row will be updated.

Upvotes: 2

Gordon Linoff
Gordon Linoff

Reputation: 1269603

These statements mean that you have written a trigger in SQL Server that is not safe. The trigger assumes that only one row has been updated. This is not safe because SQL Server calls triggers based on groups of rows.

If there is one row, then the parameters @ID and @co_ID are assigned values from that row. If there are multiple rows being updated, then values from arbitrary -- and perhaps different -- rows are assigned to the parameters.

Upvotes: 0

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