No Primary Key' error with INNER JOIN query in PostgreSQL?

Try an explicit join: SELECT devicetable. Pushid FROM devicetable JOIN usertable ON usertable. DeviceID = devicetable.

DeviceID WHERE usertable. Username =?

The JOIN clause in a SELECT has nothing to do whatsoever with primary keys. You don't need to have a primary key defined for any SELECT query. A side effect may be that you get duplicate rows, but that is a different matter entirely.

Actually, there is no explicit JOIN in your query. You could rewrite your query with an explicit JOIN like this equivalent: SELECT devicetable. Pushid FROM devicetable JOIN usertable USING (deviceID) WHERE usertable.

Username=? Read more about the JOIN syntax in the manual.

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