1. Database PL/SQL Language Reference
  2. SQL Statements for Stored PL/SQL Units
  3. DROP TYPE Statement

14.20 DROP TYPE Statement

The DROP TYPE statement drops the specification and body of an ADT, VARRAY type, or nested table type.

Topics

Prerequisites

The ADT, VARRAY type, or nested table type must be in your schema or you must have the DROP ANY TYPE system privilege.

Syntax

drop_type ::=

Description of drop_type.eps follows
Description of the illustration drop_type.eps

Semantics

schema

Name of the schema containing the type. Default: your schema.

type_name

Name of the object, varray, or nested table type to be dropped. You can drop only types with no type or table dependencies.

If type_name is a supertype, then this statement fails unless you also specify FORCE. If you specify FORCE, then the database invalidates all subtypes depending on this supertype.

If type_name is a statistics type, then this statement fails unless you also specify FORCE. If you specify FORCE, then the database first disassociates all objects that are associated with type_name and then drops type_name.

See Also:

If type_name is an ADT that is associated with a statistics type, then the database first tries to disassociate type_name from the statistics type and then drops type_name. However, if statistics have been collected using the statistics type, then the database cannot disassociate type_name from the statistics type, and this statement fails.

If type_name is an implementation type for an index type, then the index type is marked INVALID.

If type_name has a public synonym defined on it, then the database also drops the synonym.

Unless you specify FORCE, you can drop only types that are standalone schema objects with no dependencies. This is the default behavior.

See Also:

Oracle Database SQL Language Reference for information about the CREATE INDEXTYPE statement

FORCE

Drops the type even if it has dependent database objects. The database marks UNUSED all columns dependent on the type to be dropped, and those columns become inaccessible.

Note:

Oracle recommends against specifying FORCE to drop object types with dependencies. This operation is not recoverable and might make the data in the dependent tables or columns inaccessible.

VALIDATE

Causes the database to check for stored instances of this type in substitutable columns of any of its supertypes. If no such instances are found, then the database completes the drop operation.

This clause is meaningful only for subtypes. Oracle recommends the use of this option to safely drop subtypes that do not have any explicit type or table dependencies.

Example

Example 14-37 Dropping an ADT

This statement removes the ADT person_t. See "CREATE TYPE Statement" for the example that creates this ADT. Any columns that are dependent on person_t are marked UNUSED and become inaccessible. 

DROP TYPE person_t FORCE;

Related Topics