Sql queries giving low performace need to improve it

Question

Hi I have 3 table abc. select * from a select * from b where aid in (select id from a) select * from c where bid in (select Id from b where aid in (select id from a)) these quries in sp and giving correct result but as performance I need to optimise these could you please suggest how do i improve perfomance. is any tools available to optimised sql queries. Thanks

Mayur Gujrathi · Answer

write your select query and then select query and press control+l that will display estimated execution plan for query place mouse pointer over icon 'tablescan' ans note down estimated cpu cost then create clustered index like this create clustered index aid on a(id) and do the same process you will get difference

Sai Prakash · Answer

HI u can use joins for reducing the performance  but in this case the cost of table scan is going high.