Simulating an identity column within an insert trigger
- by William Jens
I have a table for logging that needs a log ID but I can't use an identity column because the log ID is part of a combo key.
create table StuffLogs
{
StuffID int
LogID int
Note varchar(255)
}
There is a combo key for StuffID & LogID.
I want to build an insert trigger that computes the next LogID when inserting log records. I can do it for one record at a time (see below to see how LogID is computed), but that's not really effective, and I'm hoping there's a way to do this without cursors.
select @NextLogID = isnull(max(LogID),0)+1
from StuffLogs where StuffID = (select StuffID from inserted)
The net result should allow me to insert any number of records into StuffLogs with the LogID column auto computed.
StuffID LogID Note
123 1 foo
123 2 bar
456 1 boo
789 1 hoo
Inserting another record using StuffID: 123, Note: bop will result in the following record:
StuffID LogID Note
123 3 bop
