INNER JOIN optimization

[Irfan Ali]

Hello,

I have some of the queries with INNER JOIN with multiple fields in WHERE caluse. I am wondering is that possible to improve query performance if we filter records first than apply equi-join ?

I tried by putting WHERE caluse up from equi-join. But EXPLAIN shows same plan as earlier. I thought if we filter records set first than apply equi join that would be much faster.

Please let me know with example. original query is as follows:

SELECT t1.empid,t1.empname,t2.deptname from employees t1
INNER JOIN departments t2
ON t1.deptid = t2.deptid
WHERE t2.deptname = 'Sales'
AND t1.empname LIKE 'p%';