Problem in doing MERGE

Question

Hi,
I have a problem in using MERGE. Say if my table called "AtmosphericParams". The primary key is AtmosphericParamsId (auto-sequence) and the unique index is TileId.
If the existing table contains:
1 | 1 | <some data>
If my AtmosphericParamsTemp table contains:
1 | 2 | <some data>
2 | 2 | <some data>
My merge statement will fail - it is trying to do an insert on the first row, which violates the constraints.
Any recommendations?
Thanks!
MERGE INTO AtmosphericParams
USING ( SELECT * FROM AtmosphericParamsTemp ) Temp
ON ( AtmosphericParams.AtmosphericParamsId = Temp.AtmosphericParamsId AND
AtmosphericParams.TileId = Temp.TileId )
WHEN MATCHED THEN
UPDATE
SET AtmosphericParams.WaterVapour = Temp.WaterVapour,
AtmosphericParams.MeasuringDate = Temp.MeasuringDate
WHEN NOT MATCHED THEN
INSERT ( AtmosphericParams.AtmosphericParamsId,
AtmosphericParams.TileId,
AtmosphericParams.WaterVapour,
AtmosphericParams.MeasuringDate )
VALUES ( Temp.AtmosphericParamsId,
Temp.TileId,
Temp.WaterVapour,
Temp.MeasuringDate );

Answer 1

The problem here is that you have both the primary key and the unique key in your ON statement. You need to decide what you want to happen in this case.
If the existing table contains:
1 | 1 | <some data>
If my AtmosphericParamsTemp table contains:
1 | 2 | <some data>
Here the record tries to insert 1 | 2 but this violates the unique key on title id. If you only have the primary key in the ON statement then this will do an update. Or is the primary key meant to be the AtmosphericParamsId and the TitleID? You need to decide.