$query =
qq|SELECT oe.id, oe.transdate, oe.reqdate, oe.quonumber, oe.transaction_description, oe.amount,
+ CASE WHEN (COALESCE(0, oe.customer_id) = 0) THEN 'vendor' ELSE 'customer' END AS vc,
c.name AS customer,
+ v.name AS vendor,
e.name AS employee
FROM oe
LEFT JOIN customer c ON (oe.customer_id = c.id)
+ LEFT JOIN vendor v ON (oe.vendor_id = v.id)
LEFT JOIN employee e ON (oe.employee_id = e.id)
WHERE (COALESCE(quotation, FALSE) = TRUE)
AND (COALESCE(closed, FALSE) = FALSE)