sql - 识别表中的重复数据

Question

如何查找具有相同身份但不同 key 的动物，即相同的“alt_anim_ident”但不同的“animals_key”

Answer 1

SELECT * 
FROM thetable t                                   -- How to find animals
WHERE EXISTS (                                    -- where (different animals) exist
        SELECT * FROM thetable x 
        WHERE x.alt_anim_ident = t.alt_anim_ident -- that have same ident
        AND x.animals_key <> t.animals_key        -- but different key
        )
ORDER BY t.alt_anim_ident, t.animals_key
        ;