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Extending Informix-Universal Server: Data Types
Chapter 5: Creating an Opaque Data Type
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Other Operations on Opaque Data Types

 This section describes the following operations that you can perform on opaque data types:

Accessing an Opaque Data Type

 Once you have created the opaque data type, the following client programs can use it once they connect to the database in which it is registered:

An opaque data type can be used in any way that other data types of the database can be used.

Dropping an Opaque Data Type

You cannot drop an opaque type if any dependencies on it still exist in the database. Therefore, to drop an opaque data type from a database, you reverse the process of registering the database, as follows:

    1. Remove or change the data type of any columns in the database that have the opaque data type as their data type.

    Use the ALTER TABLE statement to change the data type of database columns. Use the DROP TABLE statement to remove the entire table.

    2. The REVOKE statement with the USAGE ON TYPE clause removes one set of privileges assigned to the opaque data type.

    This statement removes the row of the sysxtdtypeauth system catalog table that defines the privileges of the opaque type. Use the statement to drop each set of privileges that have been assigned to the opaque type.

    3. The REVOKE statement with the EXECUTE ON FUNCTION or EXECUTE ON ROUTINE clause removes the privileges assigned to a support function of the opaque data type.

    This statement removes the row of the sysprocauth system catalog table that defines the privileges of the opaque type. Use the statement to drop each set of privileges that have been assigned to a support function. You must drop the privileges for each support function. If you assigned a specific name to the support function, use the SPECIFIC keyword to identify the specific name.

    4. The DROP CAST statement drops a casting function for a support function of an opaque data type.

    5. The DROP FUNCTION or DROP ROUTINE statement removes a support function of the opaque data type from the current database.

    6. The DROP TYPE statement removes the opaque data type from the current database.

    This statement removes the row of the sysxtdtypes system catalog table that describes the opaque data type. Once you drop an opaque type from a database, no users of that database can access the type. You must be the owner of the opaque type or have DBA privileges to remove the type.

To use these SQL statements, you must be either the owner of the object you drop or have DBA privileges. For more information on the syntax of the REVOKE, DROP FUNCTION, DROP ROUTINE, DROP CAST, and DROP TYPE statements, see their descriptions in the Informix Guide to SQL: Syntax.



Extending Informix-Universal Server: Data Types, version 9.1
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