Bulk Update and Delete Operations in EJB 3.0 JPQL

Bulk update and delete operations apply to entities of a single entity class (together with its subclasses, if any). Only one entity abstract schema type may be specified in the FROM or UPDATE clause.

The syntax of these operations is as follows:
update_statement ::= update_clause [where_clause]
update_clause ::= UPDATE abstract_schema_name [[AS] identification_variable]
                            SET update_item {, update_item}*
update_item ::= [identification_variable.]{state_field | single_valued_association_field} =
                            new_value
new_value ::=
          simple_arithmetic_expression |
          string_primary |
          datetime_primary |
          boolean_primary |
          enum_primary
          simple_entity_expression |
          NULL
delete_statement ::= delete_clause [where_clause]
delete_clause ::= DELETE FROM abstract_schema_name [[AS] identification_variable]

• A delete operation only applies to entities of the specified class and its subclasses. It does not cascade to related entities.
• The new_value specified for an update operation must be compatible in type with the state-field to which it is assigned.
• Bulk update maps directly to a database update operation, bypassing optimistic locking checks. Portable applications must manually update the value of the version column, if desired, and/or manually validate the value of the version column.
• The persistence context is not synchronized with the result of the bulk update or delete.

Caution should be used when executing bulk update or delete operations because they may result in
inconsistencies between the database and the entities in the active persistence context. In general, bulk update and delete operations should only be performed within a separate transaction or at the beginning of a transaction (before entities have been accessed whose state might be affected by such operations).

SOURCE: EJB 3.0 Persistence Specification, pages 104-105