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Oracle® Database PL/SQL Language Reference
11g Release 2 (11.2)

Part Number E17126-03
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Formal Parameter Declaration

A formal parameter declaration can appear in the following:

Topics:

Syntax

parameter_declaration ::=

parameter_declaration
Description of the illustration parameter_declaration.gif

See:

Semantics

parameter_name

The name of the formal parameter that you are declaring, which you can reference in the executable part of the subprogram.

IN, OUT, IN OUT

Mode that determines the behavior of the parameter, explained in "Subprogram Parameter Modes". The default is IN.

Note:

Avoid using OUT and IN OUT for function parameters. The purpose of a function is to take zero or more parameters and return a single value. Functions must be free from side effects, which change the values of variables not local to the subprogram.

NOCOPY

Requests that the compiler pass the corresponding actual parameter by reference instead of value (for the difference, see "Subprogram Parameter Passing Methods"). Each time the subprogram is invoked, the optimizer decides, silently, whether to obey or disregard NOCOPY.

Caution:

NOCOPY increases the likelihood of aliasing. For details, see "Subprogram Parameter Aliasing with Parameters Passed by Reference".

The compiler always ignores NOCOPY in the following cases:

datatype

The data type of the formal parameter that you are declaring. If datatype is a constrained subtype, the corresponding actual parameter inherits the NOT NULL constraint of the subtype (if it has one), but not the size (see Example 8-10).

Caution:

The data type REF CURSOR increases the likelihood of subprogram parameter aliasing, which can have unintended results. For more information, see "Subprogram Parameter Aliasing with Cursor Variable Parameters".

expression

Specifies the default value for the formal parameter. The data types of expression and the formal parameter must be compatible.

If a subprogram invocation does not specify an actual parameter for the formal parameter, then that invocation evaluates expression and assigns its value to the formal parameter.

If a subprogram invocation does specify an actual parameter for the formal parameter, then that invocation assigns the value of the actual parameter to the formal parameter and does not evaluate expression.

Examples

Related Topics

In this chapter:

In other chapters: