I have 3 different but equivalent queries. Do you mind tell me how to check and see which one has the best execution performance?
-- 1
select a from t1
where mod(a,5) = 0 and b in
( select b from t2
where c in ( SELECT c FROM t3 where mod(d,5) = 0 ));
-- 2
select t1.a from t1, t2, t3 where
t1.b = t2.b and t2.c = t3.c and mod(t1.a,5) = 0 and mod(t3.d,5) = 0;
-- 3
select t1.a from (t1 join t2 on t1.b = t2.b ) join t3 on t2.c = t3.c
where mod(t1.a,5) = 0 and mod(t3.d,5) = 0;
-- 1
select a from t1
where mod(a,5) = 0 and b in
( select b from t2
where c in ( SELECT c FROM t3 where mod(d,5) = 0 ));
-- 2
select t1.a from t1, t2, t3 where
t1.b = t2.b and t2.c = t3.c and mod(t1.a,5) = 0 and mod(t3.d,5) = 0;
-- 3
select t1.a from (t1 join t2 on t1.b = t2.b ) join t3 on t2.c = t3.c
where mod(t1.a,5) = 0 and mod(t3.d,5) = 0;
Learn from the best
Network and collaborate with thousands of CTOs, CISOs, and IT Pros rooting for you and your success.
Andrew Hancock - VMware vExpert
See if this solution works for you by signing up for a 7 day free trial.
Unlock 1 Answer and 5 Comments.
Try for 7 days”The time we save is the biggest benefit of E-E to our team. What could take multiple guys 2 hours or more each to find is accessed in around 15 minutes on Experts Exchange.
Our community of experts have been thoroughly vetted for their expertise and industry experience.
The Most Valuable Expert award recognizes technology experts who passionately share their knowledge with the community, demonstrate the core values of this platform, and go the extra mile in all aspects of their contributions. This award is based off of nominations by EE users and experts. Multiple MVEs may be awarded each year.
This award recognizes a member of Experts Exchange who has made outstanding contributions to the community within their first year as an expert. The Rookie of the Year is awarded to a new expert who has the highest number of quality contributions.