查询执行速度很慢？

Question

I have a table in which there are four column ID,MID,SID and Amt, I prepare the query for count the sum of amt using level.

Like:

SELECT Sum(amt) as level1 FROM adm where sid='MT00001';

SELECT Sum(amt) as level2 FROM adm where sid in (SELECT mid FROM adm where sid='MT00001');

SELECT Sum(amt) as level3 FROM adm where sid in (SELECT mid FROM adm where sid in (SELECT mid FROM adm where sid='MT00001'));

SELECT Sum(amt) as level4 FROM adm where sid in (SELECT mid FROM adm where sid in (SELECT mid FROM adm where sid in (SELECT mid FROM adm where sid='MT00001')))

but took so much time and i want this till level 15th

Answer 1

EXPLAIN [your query here]

This will help you understand the current status of your query and tables.

Adding Index on your table will help additional performance on your queries.