在JPQL中使用select unique并检索所有列

Question

I'm working with JPQL, I want to remove all the duplicated rows using DISTINCT , and at the same time retrieve all the columns in a table, I wrote something like this:

SELECT DISTINCT cl.name, cl.age 
FROM Client AS cl
WHERE cl.country='****'

This query returns just the two columns name and age .

Answer 1

Assuming you have a unique id you could write your query to use GROUP BY as follows:

SELECT client FROM Client client
WHERE client.id IN (
    SELECT MIN(c.id)
    FROM Client c
    WHERE c.country='****'
    GROUP BY c.name, c.age
)

You should not retrieve all the fields of Client because you should not select non-aggregated fields.

Answer 2

Try this :

DELETE from Client c
Where c.name IN (SELECT DISTINCT cl.name
                 FROM Client AS cl
                 WHERE cl.country='****')

But pay attention to your persistence context to avoid corrupt data.