Re: [SQL] Two Permance Questions

2002-09-27 Thread CoL
The select without subselect of course is better, and faster. Check your "explain analyze select ..." to se the performance, and to check the index usage if any. C. CN LIOU wrote: > Hi! > > Q1. Is subquery better or join? > > For subquery: > > SELECT t1.c1,(SELECT t2.c2 FROM t2 WHERE t2.c1 =

[SQL] Two Permance Questions

2002-09-19 Thread CN LIOU
Hi! Q1. Is subquery better or join? For subquery: SELECT t1.c1,(SELECT t2.c2 FROM t2 WHERE t2.c1 = t1.c1) FROM t1 I wonder it will loop n times if t1 returns n rows. If this is the case, is it better to use join like this: SELECT t1.c1,t2.c2 FROM t1,t2 WHERE t2.c1 = t1.c1 Q2. If the query i