Postgresql 中文操作指南
Synopsis
DROP FUNCTION [ IF EXISTS ] name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ] [, ...]
[ CASCADE | RESTRICT ]Description
DROP FUNCTION 删除现有函数的定义。要执行此命令，用户必须是函数的所有者。必须指定函数的参数类型，因为可以存在几个具有相同名称和不同参数列表的不同函数。
DROP FUNCTION removes the definition of an existing function. To execute this command the user must be the owner of the function. The argument types to the function must be specified, since several different functions can exist with the same name and different argument lists.
Parameters
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IF EXISTS
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Do not throw an error if the function does not exist. A notice is issued in this case.
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name
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The name (optionally schema-qualified) of an existing function. If no argument list is specified, the name must be unique in its schema.
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argmode
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The mode of an argument: IN, OUT, INOUT, or VARIADIC. If omitted, the default is IN. Note that DROP FUNCTION does not actually pay any attention to OUT arguments, since only the input arguments are needed to determine the function’s identity. So it is sufficient to list the IN, INOUT, and VARIADIC arguments.
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argname
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The name of an argument. Note that DROP FUNCTION does not actually pay any attention to argument names, since only the argument data types are needed to determine the function’s identity.
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argtype
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The data type(s) of the function’s arguments (optionally schema-qualified), if any.
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CASCADE
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Automatically drop objects that depend on the function (such as operators or triggers), and in turn all objects that depend on those objects (see Section 5.14).
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RESTRICT
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Refuse to drop the function if any objects depend on it. This is the default.
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Examples
此命令删除平方根函数：
This command removes the square root function:
DROP FUNCTION sqrt(integer);在一个命令中删除多个函数：
Drop multiple functions in one command:
DROP FUNCTION sqrt(integer), sqrt(bigint);如果函数名称在其模式中是唯一的，则无需参数列表即可引用它：
If the function name is unique in its schema, it can be referred to without an argument list:
DROP FUNCTION update_employee_salaries;请注意，这与以下情况不同：
Note that this is different from
DROP FUNCTION update_employee_salaries();该情况引用了一个无参数函数，而第一个变量可以引用一个包含任意数量参数（包括零个参数）的函数，前提是名称是唯一的。
which refers to a function with zero arguments, whereas the first variant can refer to a function with any number of arguments, including zero, as long as the name is unique.