IS OF type Condition

Use the IS OF type condition to test object instances based on their specific type information.

is_of_type_condition::=

Description of the illustration is_of_type_condition.gif

You must have EXECUTE privilege on all types referenced by type, and all types must belong to the same type family.

This condition evaluates to null if expr is null. If expr is not null, then the condition evaluates to true (or false if you specify the NOT keyword) under either of these circumstances:

• The most specific type of expr is the subtype of one of the types specified in the type list and you have not specified ONLY for the type, or

• The most specific type of expr is explicitly specified in the type list.

The expr frequently takes the form of the VALUE function with a correlation variable.

The following example uses the sample table oe.persons, which is built on a type hierarchy in "Substitutable Table and Column Examples". The example uses the IS OF type condition to restrict the query to specific subtypes:

SELECT * FROM persons p 
   WHERE VALUE(p) IS OF TYPE (employee_t);

NAME                     SSN
----------------------------
Joe                    32456
Tim                     5678

SELECT * FROM persons p 
   WHERE VALUE(p) IS OF (ONLY part_time_emp_t);

NAME                     SSN
----------------------------
Tim                     5678