Logic for this requirement

Question

Hi friends,
I get salary from different tables... like for example
m_sal and e_sal..if the salary is null in m_sal i have to select salary from e_sal and viceversa
can you pls tell me how to do this
Thanks

Answer 1

You would still use COALESCE
SQL> with
  2  emp as
  3      (
  4      select 1 empno from dual union all
  5      select 2 empno from dual union all
  6      select 3 empno from dual union all
  7      select 4 empno from dual union all
  8      select 5 empno from dual union all
  9      select 6 empno from dual
10      ),
11  sal1 as
12      (
13      select 1 empno, 100 esal from dual union all
14      select 3 empno, 200 esal from dual union all
15      select 5 empno, 100 esal from dual union all
16      select 6 empno, 300 esal from dual
17      ),
18  sal2 as
19      (
20      select 2 empno, 600 msal from dual union all
21      select 4 empno, 500 msal from dual
22      )
23  select
24      e.empno,
25      coalesce
26          (
27              (select sal1.esal from sal1 where sal1.empno = e.empno),
28              (select sal2.msal from sal2 where sal2.empno = e.empno)
29          ) sal
30  from
31      emp e;
     EMPNO        SAL
         1        100
         2        600
         3        200
         4        500
         5        100
         6        300
6 rows selected.