Question

I just imported a large amount of data into two tables. Let’s call them shipments and returns.

When trying to do a simple join (left or inner) based on any criteria in these two tables. query looks like it tries to do a cross join or find every combination instead of what the query should be pulling.

each table has an PK id field, but there is not FK relationship between the two other than some shared field.

I’m currently just trying to related them on shipment_id.

I feel this is a simple answer. Am I missing a reference or something obvious that is causing this? Thanks!

here’s an example. This should returned under 100 rows. This instead returns hundreds of thousands.

SELECT r.*

FROM returns as r

left outer join shipments as s

on r.shipment_id = s.shipment_id

where r.date = '2011-06-20'

Answer 1

The issue turned out to be very simple, just not readily apparent until going through all the columns. It turns out that the shipment ID was duplicated through every row as it hit the upper limit for the int datatype. This is why joins were returning every record.

After switching the datatype to bigint and reimporting, everything worked great. Thanks all for looking into it.