How do i group by date only from date time field in JPQL

Question

For mysql I wrote a query like

SELECT * FROM mytable GROUP BY DATE(dateTimeField)

But i can\'t use the DATE() function in JPQL

Answer 1

If You use Hibernate under the hood you can try :

1. Create your own dialect with custom function

   public class CustomPostgresqlDialect extends PostgreSQLDialect {   
       public CustomPostgresqlDialect() {
           super();
           registerFunction("truncate_date",
           new SQLFunctionTemplate( StandardBasicTypes.TIMESTAMP, "DATE(?1)" ));
       }
   }
   

2. Register Your dialect in persistence.xml

3. Use your function in JPQL.

   select p from Post p group by truncate_date(p.dateCreated)