从子查询的结果更新

Question

Hi i want upadte a data from the result of a subquery

UPDATE A
SET A.a = (select a from A inner join B on B.b=A.c and 
        B.cf='RGNVQE63H48J869P'  and B.b=2345 and
        CAST(A.a as decimal)>1);

I want that Aa=result of a subquery.

Answer 1

Use a correlated subquery. Your code has an issue because the table being updated is repeated in the subquery:

UPDATE A
    SET A.a = (SELECT b.a 
               FROM B 
               WHERE B.b = A.c AND 
                     B.cf = 'RGNVQE63H48J869P' AND
                     B.b = 2345 and
                     CAST(A.a as decimal) > 1
              );

Notes:

• If the subquery returns more than one row, this will result in an error.
• If the subquery returns no rows, then 0 will be assigned.

This answers the question you have asked here. If this doesn't do what you really need, ask a new question with sample data, desired results, an appropriate database tag, and a clear explanation of what you want to do.