DROP PROCEDURE

DROP PROCEDURE

7

SQL - Language Statements

DROP PROCEDURE

remove a procedure

DROP PROCEDURE \[ IF EXISTS \]

name

\[ ( \[ \[

argmode

\] \[

argname

\]

argtype

\[, \...\] \] ) \] \[, \...\] \[ CASCADE \| RESTRICT \]

Description
===========

`DROP PROCEDURE` removes the definition of one or more existing
procedures. To execute this command the user must be the owner of the
procedure(s). The argument types to the procedure(s) usually must be
specified, since several different procedures can exist with the same
name and different argument lists.

Parameters
==========

`IF EXISTS`

:   Do not throw an error if the procedure does not exist. A notice is
    issued in this case.

name

:   The name (optionally schema-qualified) of an existing procedure.

argmode

:   The mode of an argument: `IN`, `OUT`, `INOUT`, or `VARIADIC`. If
    omitted, the default is `IN` (but see below).

argname

:   The name of an argument. Note that `DROP PROCEDURE` does not
    actually pay any attention to argument names, since only the
    argument data types are used to determine the procedure\'s identity.

argtype

:   The data type(s) of the procedure\'s arguments (optionally
    schema-qualified), if any. See below for details.

`CASCADE`

:   Automatically drop objects that depend on the procedure, and in turn
    all objects that depend on those objects (see [???](#ddl-depend)).

`RESTRICT`

:   Refuse to drop the procedure if any objects depend on it. This is
    the default.

Notes {#sql-dropprocedure-notes}
=====

If there is only one procedure of the given name, the argument list can
be omitted. Omit the parentheses too in this case.

In PostgreSQL, it\'s sufficient to list the input (including `INOUT`)
arguments, because no two routines of the same name are allowed to share
the same input-argument list. Moreover, the `DROP` command will not
actually check that you wrote the types of `OUT` arguments correctly; so
any arguments that are explicitly marked `OUT` are just noise. But
writing them is recommendable for consistency with the corresponding
`CREATE` command.

For compatibility with the SQL standard, it is also allowed to write all
the argument data types (including those of `OUT` arguments) without any
argmode markers. When this is done, the types of the procedure\'s `OUT`
argument(s) *will* be verified against the command. This provision
creates an ambiguity, in that when the argument list contains no argmode
markers, it\'s unclear which rule is intended. The `DROP` command will
attempt the lookup both ways, and will throw an error if two different
procedures are found. To avoid the risk of such ambiguity, it\'s
recommendable to write `IN` markers explicitly rather than letting them
be defaulted, thus forcing the traditional PostgreSQL interpretation to
be used.

The lookup rules just explained are also used by other commands that act
on existing procedures, such as `ALTER PROCEDURE` and
`COMMENT ON PROCEDURE`.

Examples {#sql-dropprocedure-examples}
========

If there is only one procedure `do_db_maintenance`, this command is
sufficient to drop it:

    DROP PROCEDURE do_db_maintenance;

Given this procedure definition:

    CREATE PROCEDURE do_db_maintenance(IN target_schema text, OUT results text) ...

any one of these commands would work to drop it:

    DROP PROCEDURE do_db_maintenance(IN target_schema text, OUT results text);
    DROP PROCEDURE do_db_maintenance(IN text, OUT text);
    DROP PROCEDURE do_db_maintenance(IN text);
    DROP PROCEDURE do_db_maintenance(text);
    DROP PROCEDURE do_db_maintenance(text, text);  -- potentially ambiguous

However, the last example would be ambiguous if there is also, say,

    CREATE PROCEDURE do_db_maintenance(IN target_schema text, IN options text) ...

Compatibility {#sql-dropprocedure-compatibility}
=============

This command conforms to the SQL standard, with these PostgreSQL
extensions:

-   The standard only allows one procedure to be dropped per command.

-   The `IF EXISTS` option is an extension.

-   The ability to specify argument modes and names is an extension, and
    the lookup rules differ when modes are given.

See Also
========
