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Update Field based on another table's values

开发者 https://www.devze.com 2022-12-12 13:14 出处:网络
Is there a more elegant way to write the following Microsoft SQL Server 2008 command? UPDATE TableB SET TableBField2=0

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
0

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