That is because OpenERP does not store that information directly into Postgres. It is based on a calculated field that gets updated everytime it is triggered within OpenERP. For example, when a stock move is set to the specified location.

If you want an overview outside of Postgres, just go the specified location and print out the stock report.

If you must do this within postgres then you should loop over the stock_move table and calculate based on the product_id, destination_location_id and source_location_id (or something like that).

thank Ludo, and is the same for inserting a products? i have to insert data into much tables?