ALTER USER MAPPING
ALTER USER MAPPING — change the definition of a user mapping
Synopsis
ALTER USER MAPPING FOR { user_name | USER | 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_USERand- USERmatch the name of the current user.- PUBLICis 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- DROPspecify the action to be performed.- ADDis 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, Postgres Pro diverges from the standard here in the interest of consistency and interoperability. 

