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in (id_1,id_2, ...) or more select statements or
Posted by: Steven Chan
Date: December 08, 2004 11:34PM


I am designing a web application. Table A is a list of customers and table B is a list of items each customer has purchased. pri_key of A is customer_id and there is an index on customer_id in B.

I need to return cutomers names as well as addresses and descriptions (large text field) from Table A as well as return the count of purchases from Table B.

At any 1 time, a query will only return about 20 customers because I limit it.

Which is the best performance wise:

a) Join A to B and group by customer_id, name, address, description
b) select customers from A. Loop through them to build a string of customer_ids like id_1,id_2,id_3... and then select from B dropping the string into an IN() in the WHERE clause.
c) select from A. Then:
select from B where customer_id = id_1
select from B where customer_id = id_2
select from B where customer_id = id_3

Thanks in advance

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in (id_1,id_2, ...) or more select statements or
December 08, 2004 11:34PM

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