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Help Center/ GaussDB/ Developer Guide(Distributed_V2.0-3.x)/ SQL Reference/ SQL Syntax/ ALTER TYPE

ALTER TYPE

Updated on 2024-05-07 GMT+08:00

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Description

Modifies the definition of a type.

Precautions

Only the owner of a type, a user granted the ALTER permission on a type, or a user granted the ALTER ANY TYPE permission on a sequence can run the ALTER TYPE command. The system administrator has this permission by default. To modify the owner or schema of a type, you must be a type owner or system administrator and a member of the new owner role.

Syntax

Modify a type.

      
         ALTER TYPE name action [, ... ]
ALTER TYPE name OWNER TO { new_owner | CURRENT_USER | SESSION_USER }
ALTER TYPE name RENAME ATTRIBUTE attribute_name TO new_attribute_name [ CASCADE | RESTRICT ]
ALTER TYPE name RENAME TO new_name
ALTER TYPE name SET SCHEMA new_schema
ALTER TYPE name ADD VALUE [ IF NOT EXISTS ] new_enum_value [ { BEFORE | AFTER } neighbor_enum_value ] 
ALTER TYPE name RENAME VALUE existing_enum_value TO new_enum_value

where action is one of:
    ADD ATTRIBUTE attribute_name data_type [ COLLATE collation ] [ CASCADE | RESTRICT ]
    DROP ATTRIBUTE [ IF EXISTS ] attribute_name [ CASCADE | RESTRICT ]
    ALTER ATTRIBUTE attribute_name [ SET DATA ] TYPE data_type [ COLLATE collation ] [ CASCADE | RESTRICT ]

Change the owner of a type.

     
        ALTER TYPE name OWNER TO { new_owner | CURRENT_USER | SESSION_USER }

Change the name of a type.

     
        ALTER TYPE name RENAME TO new_name
ALTER TYPE name RENAME ATTRIBUTE attribute_name TO new_attribute_name [ CASCADE | RESTRICT ]

Move a type to a new schema.
1

ALTER TYPE name SET SCHEMA new_schema

Add a new value to an enumerated type.

     
        ALTER TYPE name ADD VALUE [ IF NOT EXISTS ] new_enum_value [ { BEFORE | AFTER } neighbor_enum_value ]

Change an enumerated value in the value list.

     
        ALTER TYPE name RENAME VALUE existing_enum_value TO new_enum_value

Parameters

name
Specifies the name of an existing type that needs to be modified (optionally schema-qualified).

new_name
Specifies the new name of the type.

new_owner
Specifies the new owner of the type.

new_schema
Specifies the new schema of the type.

attribute_name
Specifies the name of the attribute to be added, modified, or deleted.

new_attribute_name
Specifies the new name of the attribute to be renamed.

data_type
Specifies the data type of the attribute to be added, or the new type of the attribute to be modified.
new_enum_value
Specifies a new enumerated value. It is a non-null string with a maximum length of 64 bytes.
neighbor_enum_value
Specifies an existing enumerated value before or after which a new enumerated value will be added.
existing_enum_value
Specifies an enumerated value to be changed. It is a non-null string with a maximum length of 64 bytes.

CASCADE
Determines that the type to be modified, its associated records, and subtables that inherit the type will all be updated.
RESTRICT
Refuses to update the associated records of the modified type. This is the default action.
NOTICE:
- ADD ATTRIBUTE, DROP ATTRIBUTE, and ALTER ATTRIBUTE can be combined for processing. For example, it is possible to add several attributes or change the types of several attributes at the same time in one command.
- To modify a schema of a type, you must have the CREATE permission on the new schema. To alter the owner, you must be a direct or indirect member of the new owner role, and that member must have CREATE permission on the schema of this type (these restrictions enforce that the alter owner will not do anything that cannot be done by deleting and rebuilding the type). However, the system administrator can modify the rights of any type in any way. To add an attribute or modify the type of an attribute, you must also have the USAGE permission of this type.
- CURRENT_USER
  Specifies the current user.
- SESSION_USER
  Specifies the current system user.
- COLLATE collation
  Assigns a collation to the column, which must be a sortable data type. If the collation is not specified, the default collation for the column's data type is used.

Examples

See Examples in section "CREATE TYPE."

Helpful Links

CREATE TYPE and DROP TYPE

Parent topic: SQL Syntax

Previous topic: ALTER TRIGGER

Next topic: ALTER USER

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