How to perform date operations in hibernate

Question

I want to perform data time operations using hibernate HQL.

I want to add and subtract two dates as well as I want to subtract 1 year or 1 month from a particular da

Answer 1

See Performing Date/Time Math In HQL? for an example.

To use custom sql you must wrote an own hibernate dialect and register:

registerFunction("weekday", 
  new SQLFunctionTemplate(Hibernate.INTEGER, "to_char(?1,'D')") );