Oracle® Database PL/SQL Language Reference 11g Release 2 (11.2) Part Number E17126-08 |
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A formal parameter declaration can appear in the following:
See:
Name of the formal parameter that you are declaring, which you can reference in the executable part of the subprogram.
Mode that determines the behavior of the parameter, explained in "Subprogram Parameter Modes". Default: IN
.
Note:
Avoid usingOUT
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.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 these cases:
The actual parameter must be implicitly converted to the data type of the formal parameter.
The actual parameter is the element of an associative array.
The actual parameter is a scalar variable with the NOT
NULL
constraint.
The actual parameter is a scalar numeric variable with a range, size, scale, or precision constraint.
The actual and formal parameters are records, one or both was declared with %ROWTYPE
or %TYPE
, and constraints on corresponding fields differ.
The actual and formal parameters are records, the actual parameter was declared (implicitly) as the index of a cursor FOR
LOOP
statement, and constraints on corresponding fields differ.
The subprogram is invoked through a database link or as an external subprogram.
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 typeREF
CURSOR
increases the likelihood of subprogram parameter aliasing, which can have unintended results. For more information, see "Subprogram Parameter Aliasing with Cursor Variable Parameters".Default value of the formal parameter that you are declaring. The data type of expression
must be compatible with datatype
.
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
.
Example 2-26, "Assigning Value to Variable as IN OUT Subprogram Parameter"
Example 8-12, "Parameter Values Before, During, and After Procedure Invocation"
Example 8-13, "OUT and IN OUT Parameter Values After Unhandled Exception"
Example 8-19, "Adding Subprogram Parameter Without Changing Existing Invocations"