I am trying to query multiple tables with one query, but I am having troubles with the query. When I execute it, I get double values. The result appears twice in the list. Could someone please help me and tell me what I am doing wrong
The query:
开发者_如何学PythonSELECT distinct *
FROM asset, inuse, location, user_asset
WHERE asset.aid = 95
and asset.aid = location.asset_location_id
and asset.aid = asset_usage_id
and asset_id = asset.aid
ORDER BY name ASC
The tables location,user_asset have 1 - N relationship with asset and inuse has 1-1 relationship. I assumed that DISTINCT would get rid of the problem of multiple copies. asset.aid is unique value, but is used multible times in other tables.
I get all the values on the screen, but for some reason they are shown twice.
Thank you!
That means that either:
- you don't have only one-to-one relationships between
asset
and the other tables - or asset.aid is not a unique field, and you have several entries matching
asset.aid = 95
As advised by mu is too short, you won't get reliable help without providing your table structure.
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