Postgresql 中文操作指南
Synopsis
DROP AGGREGATE [ IF EXISTS ] name ( aggregate_signature ) [, ...] [ CASCADE | RESTRICT ]
where aggregate_signature is:
* |
[ argmode ] [ argname ] argtype [ , ... ] |
[ [ argmode ] [ argname ] argtype [ , ... ] ] ORDER BY [ argmode ] [ argname ] argtype [ , ... ]Description
DROP AGGREGATE 删除一个现有聚合函数。要执行此命令，当前用户必须是聚合函数的所有者。
DROP AGGREGATE removes an existing aggregate function. To execute this command the current user must be the owner of the aggregate function.
Parameters
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IF EXISTS
-
Do not throw an error if the aggregate does not exist. A notice is issued in this case.
-
-
name
-
The name (optionally schema-qualified) of an existing aggregate function.
-
-
argmode
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The mode of an argument: IN or VARIADIC. If omitted, the default is IN.
-
-
argname
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The name of an argument. Note that DROP AGGREGATE does not actually pay any attention to argument names, since only the argument data types are needed to determine the aggregate function’s identity.
-
-
argtype
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An input data type on which the aggregate function operates. To reference a zero-argument aggregate function, write * in place of the list of argument specifications. To reference an ordered-set aggregate function, write ORDER BY between the direct and aggregated argument specifications.
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CASCADE
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Automatically drop objects that depend on the aggregate function (such as views using it), and in turn all objects that depend on those objects (see Section 5.14).
-
-
RESTRICT
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Refuse to drop the aggregate function if any objects depend on it. This is the default.
-
Notes
有关引用有序集聚合的替代语法，请参见 ALTER AGGREGATE 。
Alternative syntaxes for referencing ordered-set aggregates are described under ALTER AGGREGATE.
Examples
要为类型 integer 删除聚合函数 myavg ：
To remove the aggregate function myavg for type integer:
DROP AGGREGATE myavg(integer);要删除假想集聚合函数 myrank ，该函数使用任意排序的列列表和匹配的直接参数列表：
To remove the hypothetical-set aggregate function myrank, which takes an arbitrary list of ordering columns and a matching list of direct arguments:
DROP AGGREGATE myrank(VARIADIC "any" ORDER BY VARIADIC "any");要在单个命令中删除多个聚合函数：
To remove multiple aggregate functions in one command:
DROP AGGREGATE myavg(integer), myavg(bigint);