SQL Query using Hibernate in a Restful Web Service [duplicate]

问题

Possible Duplicate:
SQL Query with MySQL

I implement a Rest Web Service (JAX-RS) using Jersey in Java. I use hibernate to fetch the data from MySQL database. With this query:

(Select distinct deliverable.id from Task as t where t.project.id= :id And t.user.username = :name order by t.id desc")
                    .setMaxResults(3)
                    .setLong("id", projectId)
                    .setString("name", username)
                    .list();

I have a right result which is : [275,51,286]. This is the provided key for every id in the database:

    id       key
---------------------
    275      2.0
    51       cm
    286      19.87

Now I use this query (Everything is the same except deliverable.key instead of deliverable.id) :

(Select distinct deliverable.key from Task as t where t.project.id= :id And t.user.username = :name order by t.id desc")
                    .setMaxResults(3)
                    .setLong("id", projectId)
                    .setString("name", username)
                    .list();

The result is: ["2.0","19.88","19.99"]. The first one is right, but the second and third one are completely different keys.

Maybe it can be solved by "alias" or any other way. your suggestion?

回答1:

I found the answer:

("select d.key from Deliverable as d, Task as t
                where t.deliverable.id = d.id and
                t.id = (select max(t1.id) from Task t1 where t1.deliverable.id = d.id)
                and d.project.id= :id
                and t.user.username = :name
                order by t.id desc")
        .setMaxResults(3)
        .setLong("id", projectId)
        .setString("name", username)
        .list();

来源：https://stackoverflow.com/questions/11457292/sql-query-using-hibernate-in-a-restful-web-service

标签

mysql

hibernate

jersey

jax-rs