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sql-serverif-statementsql-update
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Reputation: 2627

SQL Server If statement to update table value

I'm trying write a routine in SQL Server that, when run, would traverse specified tables and, if a specific column contains a value, update another value. In pseudo code:

 select * from table1
 if column1 = true
 {
     update table2.column1 with value where table2.column2.value = table1.column2.value
 }

Basically, traverse table1 and if the value in a specific column is true, update the value of another table's column1 where that row's column2 matches table1's column2

Thanks

Upvotes: 0

Views: 3201

Answers (2)

Elroy Flynn
Elroy Flynn

Reputation: 3218

Not sure I fully understand your requirement, but if you want update all the values using a single update statement this might do:

update table2 set column1 = 
       (select column1 from table1 t1 
        where  t1.column2 = table2.column2
       )
    where exists 
       (select *  from table1 t1 
        where t1.column2 = table2.column2 and t1.column1 = true
       )

It could be written to avoid having the 2nd subselect (the EXISTS clause) but the solution is rather dialect-specific. This one is, I believe, more likely to be accepted in an unknown dialect. (Except for the word "true" ... substitute the value you want, there. )

Upvotes: 0

JNK
JNK

Reputation: 65147

You don't need the IF, just use a WHERE clause:

UPDATE T2
SET t2.Column1 = 'blah'
FROM Table2 t2
INNER JOIN Table1 t1
   ON t1.value = t2.value
WHERE t1.column1 = 'True'

Upvotes: 3

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