HQL两列之间的差异之和

Question

A simple hibernate related question. How can I do something equivalent to this SQL code :

    select sum(COLUMN_A - COLUMN_B) from some_table;

I tried using both columns inside the sum property like this:

    Projections.sum("COLUMN_A - COLUMN_B")

With no success once hibernate will search for a property called COLUMN_A - COLUMN_B which obviously does not exist.

Any alternatives ?

Answer 1

Have you tried a Projections.sqlProjection ?

Something like

Projections.sqlProjection("SUM(COLUMN_A - COLUMN_B) as sumOfDifferences", new String[]{"sumOfDifferences"}, new Type[] {IntegerType.INSTANCE})