Update Field based on another table's values
Is there a more elegant way to write the following Microsoft SQL Server 2008 command?
UPDATE TableB
SET TableBField2=0
WHERE TableBID IN(
SELECT TableBID
FROM TableB
JOIN TableA on TableB.TableAID=TableA.TableAID
WHERE TableBField2 < 0
AND TableAField1 = 0
)
In plain speak, what I'm doing is updating a table based on the value of a field in a joined table. I wonder if my use of IN() i开发者_如何学运维s considered inefficient.
This should be more efficient:
UPDATE TableB b
SET TableBField2=0
WHERE exists (
SELECT 1
FROM TableA
WHERE b.TableAID=TableA.TableAID
AND b.TableBField2 < 0
AND TableAField1 = 0
)
You can try something like this
UPDATE TableB
SET Field2 = 0
FROM TableB b INNER JOIN
TableA a ON b.TableB.TableAID=a.TableAID
WHERE b.Field2 < 0
AND a.Field1 = 0
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