I'm creating a sproc that will insert rows into a 'staging' table with an insert into + subquery like so:
INSERT INTO myStagingTable SELECT col1, col2, col3 FROM myRealTable I need to put a conditional in there somehow to determine if the value from col1 for example already exists on myStagingTable, then don't insert it, just skip that row from myRealTable.
is this possible? If so, how would I structure that?
TIA
INSERT INTO myStagingTable SELECT col1, col2, col3 FROM myRealTable rt WHERE NOT EXISTS ( SELECT rt.col1, rt.col2, rt.col3 INTERSECT SELECT col1, col2, col3 FROM myStagingTable ) This will handle all duplicates (including NULL)
Note that is will insert the duplicates from the real table is any. Say if the real table contains
1 1 1 1 1 1 and the staging table contains
2 2 2 , both records with 1, 1, 1 will be inserted.
If you want to eliminate the duplicates on insert (so that only one instance of 1, 1, 1 is inserted), then just use this:
INSERT INTO myStagingTable SELECT col1, col2, col3 FROM myRealTable EXCEPT SELECT col1, col2, col3 FROM myStagingTable 
