Beginning SQL - adding the values of one column to another from separate tables

Question

I am currently taking my first course in SQL and have encountered a bit of a problem. I will now try to explain what I am trying to do. I have this select statement which properly displays what I need. MY problem arises when I try to convert it into an UPDATE statement instead.

SELECT infobb02.uni+tempbb02.sal
from infobb02 JOIN tempbb02 ON infobb02.empno=tempbb02.empno;

In case its not obvious im adding value of uni from table infobb02 to sal in table tempbb02. I have tried all sorts of things to get it to be a permanent update but keep getting errors mostly

"SQL command not properly ended"

Any help is appreciated! Thanks.

Answer 1

Assuming that your query is:

SELECT i.uni + t.sal
FROM infobb02 i JOIN
     tempbb02 t
     ON i.empno = t.empno;

If you want to update tempbb02 , then:

update tempbb02 t
    set t.sal = t.sal +
                (select i.uni from infobb02 i where i.empno = t.empno)
    where exists (select 1 from infobb02 i where i.empno = t.empno);

Answer 2

Instead of using an UPDATE statement, you could use a MERGE:

merge into tempbb02 tgt
using infobb02 src
  on (tgt.empno = src.empno)
when matched then
update set tgt.sal = tgt.sal + src.uni;