Question

Apologies if the title does not accurately describe the question (which it probably doesn’t). I have the following two tables :-

tLiveTable:

PieceID      LocationRef
------------------------
100              5

tPieceTable:

ID    BatchNo      PieceNumber
------------------------------
50    ABC          X1
100   ABC          X1

How can I update the LocationRef for that piece in tLiveTable given only the BatchNo and PieceNo?

I’ve tried the following:

UPDATE tLiveTable
SET LocationRef = 'blabla unimportant'
WHERE
PieceID = (SELECT ID FROM tPieceTable WHERE (BatchNo = 'ABC') AND (PieceNo = 'X1'))

But there can be multiple entries in tPieceTable with an identical BatchNo and PieceNo. I want to only retrieve the ID from tPieceTable whose ID is currently the one in the tLiveTable.

Should I really be using an INNER JOIN for this?

Answer 1

Your query will not work as SELECT ID FROM tPieceTable WHERE (BatchNo = 'ABC') AND (PieceNo = 'X1') returns more than one ID

Try this;

UPDATE L SET LocationRef = 'blabla unimportant'
FROM tLiveTable L JOIN tPieceTable P 
     ON L.PieceID = P.ID
WHERE (P.BatchNo = 'ABC') AND (P.PieceNo = 'X1')

Or using IN for =

UPDATE tLiveTable
SET LocationRef = 'blabla unimportant'
WHERE
PieceID IN (SELECT ID FROM tPieceTable WHERE (BatchNo = 'ABC') AND (PieceNo = 'X1'))