> For the complete documentation index, see [llms.txt](https://docs.postgresql.tw/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.postgresql.tw/reference/sql-commands/sql-alterusermapping.md).

# ALTER USER MAPPING

### ALTER USER MAPPING

ALTER USER MAPPING — change the definition of a user mapping

### Synopsis

```

ALTER USER MAPPING FOR { user_name | USER | CURRENT_ROLE | CURRENT_USER | SESSION_USER | PUBLIC }
    SERVER server_name
    OPTIONS ( [ ADD | SET | DROP ] option ['value'] [, ... ] )
```

### Description

`ALTER USER MAPPING` changes the definition of a user mapping.

The owner of a foreign server can alter user mappings for that server for any user. Also, a user can alter a user mapping for their own user name if `USAGE` privilege on the server has been granted to the user.

### Parameters

*`user_name`* : User name of the mapping. `CURRENT_ROLE`, `CURRENT_USER`, and `USER` match the name of the current user. `PUBLIC` is used to match all present and future user names in the system.

*`server_name`* : Server name of the user mapping.

`OPTIONS ( [ ADD | SET | DROP ] option ['value'] [, ... ] )` : Change options for the user mapping. The new options override any previously specified options. `ADD`, `SET`, and `DROP` specify the action to be performed. `ADD` is assumed if no operation is explicitly specified. Option names must be unique; options are also validated by the server's foreign-data wrapper.

### Examples

Change the password for user mapping `bob`, server `foo`:

```

ALTER USER MAPPING FOR bob SERVER foo OPTIONS (SET password 'public');
```

### Compatibility

`ALTER USER MAPPING` conforms to ISO/IEC 9075-9 (SQL/MED). There is a subtle syntax issue: The standard omits the `FOR` key word. Since both `CREATE USER MAPPING` and `DROP USER MAPPING` use `FOR` in analogous positions, and IBM DB2 (being the other major SQL/MED implementation) also requires it for `ALTER USER MAPPING`, PostgreSQL diverges from the standard here in the interest of consistency and interoperability.

### See Also

[CREATE USER MAPPING](/reference/sql-commands/sql-createusermapping.md), [DROP USER MAPPING](/reference/sql-commands/sql-dropusermapping.md)

***

原文：[PostgreSQL 18.6 Documentation](https://www.postgresql.org/docs/18/sql-alterusermapping.html)（英文原文，待翻譯）


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