Hibernate Criteria Projection without mapped association of tables

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醉酒成梦
醉酒成梦 2021-01-01 06:47

I have 2 tables say

Table1 and Table2

Now Table1 has 3 columns say t1, t2, t3 and Table2 has 2 columns t4 and t5.

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  • 2021-01-01 07:07

    Yes, this is supported in Hibernate. The only thing here is that we have to use HQL:

    • 16.2. The from clause (cite:)

    Multiple classes can appear, resulting in a cartesian product or "cross" join.

    from Formula, Parameter
    from Formula as form, Parameter as param
    

    So in our case:

    session
       .createQuery("SELECT t1.prop1, t1.prop2, t1.prop3 "
                  + "       t2.prop4, t2.prop5 "
                  + " FROM Entity1 AS t1, Entity2 As t2 " +
                  // if there is some relation - unmapped
                  + " WHERE t1.someProperty = t2.someProperty "
                  + "   AND ... "
                  )
       .setMaxResults(10) // we can even page here
       .list() 
    

    NOTE: I used prop1, prop2 and Entity1, Entity2 ... to force the feeling that this is HQL. We are talking about mapped entities, not tables or columns

    And we will recieve collection of object[] array...

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