Help with a query on sales to new customers

[marc312]

Can someone please help me with some query syntax? I'm trying to do a joint query to find total sales for orders which were a customer's first order only. Basically, I need to join these two queries, which I already know work in their own respects:

 

Take total sales for all orders:

select sum(ot.value) as total from orders o, orders_total ot where ot.class='ot_total' and ot.orders_id=o.orders_id

 

Find first orders:

select distinct(o.customers_id) from orders o, customers_info ci where ci.customers_info_id = o.customers_id

 

It seems to me that I should be able to join these in the following way:

select sum(ot.value) as total from orders o, orders_total ot where ot.class='ot_total' and ot.orders_id=o.orders_id in (select distinct(o.customers_id) from orders o, customers_info ci where ci.customers_info_id = o.customers_id)

 

However, the above makes my database server hang.

 

Any suggestions? I'd really appreciate the help!

 

-Marc