如何创建存储过程？

Question

I have the following records generated through some sql joins.

ID SYSTEM   CODE
1  W         A
2  W         NULL
3  W         NULL
4  W         B
5  U         X

In the above generated records I need to update all the records CODE as 'X' since the SYSTEM U has X in it. Please note this CODE which is I'm updating is from some table say CODES_TABLE. How do I do that through stored procedure? DO I have to create some temp table to hold these vales somewhere? Thanks in advance

Answer 1

Is this what you want?

update t
    set code = (select t2.code from t t2 where t2.system = 'U')
    where t2.system <> 'U';

EDIT:

Or, for a query, just use analytic functions:

select t.*, max(case when system = 'U' then code end) over () as u_code
from t;