Question

In DB2, using the following left join

select a.deptno, a.deptname, b.empno
from #dept a
left join #emp b
on a.deptno = b.workdept

on two tables, gets me a list like:

dpt  name         emp
----------------------
A01  ACCOUNTING   5001
A02  PAYROLL      NULL
A03  OPERATIONS   5003
A03  OPERATIONS   5004
A03  OPERATIONS   5007
A05  MAINTENANCE  NULL

but I want only the first instance of any dpt. Is there a way to code the left join to pull only the first occurrence, so that it would look like:

dpt  name         emp
----------------------
A01  ACCOUNTING   5001
A02  PAYROLL      NULL
A03  OPERATIONS   5003
A05  MAINTENANCE  NULL

Answer 1

You can try something like

select a.deptno, a.deptname, min(b.empno)
from #dept a
left join #emp b
on a.deptno = b.workdept
group by a.deptno, a.deptname