问题
I have an object Favourite. This object has a many to many connection with Colors. Lets say that some favourites have many colors, 2-3 etc. When I search for a favourite like:
SELECT fav FROM Favourite fav join fetch fav.colors as cl WHERE fav.name = "blabla" .
The resulting object contains all the colors related to this favourite. My problem is when I want to search for a favourite that has a certain color. For example:
SELECT fav FROM Favourite fav join fetch fav.colors as cl WHERE cl.name = "red"
Then the resulting object contains only the red color. I want to get as a result the fav objects that contain the "red" color, but also show all the related colors. Any suggestions? Thanks in advance.
回答1:
Well finally it worked with an inner query and "EXISTS" operator. (color is an object of , int id and string name).
SELECT fav FROM Favourite fav join fetch fav.colors as cl WHERE EXISTS ( SELECT fav2 FROM Favourite fav2 join fetch fav2.colors as cl2 WHERE fav2.id = fav.id AND cl2.name = "red" )
来源：https://stackoverflow.com/questions/12051559/jpa-join-fetch-query-with-many-to-many