EJB QL Restrictions

EJB QL has a few restrictions:

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To compare date and time values in an EJB QL query, use long primitives to represent the values as milliseconds. Do not use the java.util.Date and java.sql.Time objects in EJB QL comparisons.
Because support for BigDecimal and BigInteger types is optional for EJB 2.1 containers, applications that use these types in EJB QL queries may not be portable.
Currently, container-managed persistence does not support inheritance. For this reason, two entity beans of different types cannot be compared.