Question

I have a problem with a query:
I have a table with a list of orders placed by customers

orders: customer_id, payment_method ...some other field

I need to extract the customer_id and a ‘YES’ if the customer has made ​​at least one payment with a specific mode of payment

I tried something like this:

SELECT DISTINCT o.customer_id, 
CASE WHEN o.payment_method = 10 THEN 'YES' ELSE 'NO' END AS credit_card
FROM orders AS o
WHERE o.year = 2012
ORDER BY o.customer_id

but in case the customer has made ​​payments with different payment methods are shown two records, one with ‘YES’ one with a ‘NO’… it’s possible to get only one value?

Answer 1

SELECT   o.customer_id, 
         IF(MAX(IF(o.payment_method=10, 1, 0)) = 1, 'YES', 'NO') credit_card
FROM     orders o
WHERE    o.year = 2012
GROUP BY o.customer_id