sql select statement

table a has a column a_id;
table b has a column b_id;
I need select the rows where the a_id=b_id;

select * from a where a.a_id=b.b_id
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Daniel ReynoldsSoftware Applications Developer / IntegratorCommented:
that should work fine
That'll work if you want to go through table b row-by-row.  What you may want to do instead is use some type of JOIN statement.  Since you tagged MySQL as the database type, check the My SQL Reference Manual for more information on how to do that.
SharathData EngineerCommented:
Where is table b in your query? Any of these will work.
select * from a where a_id in (select b_id from b)

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select a.* from a inner join b on a.a_id = b.b_id

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select * from a where exists (select 1 from b where a_id = b_id)

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MySQL Server

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