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Chapter 3. Laying the Groundwork: PL/SQL... > Parameters of subprograms

Parameters of subprograms

In previous examples, we show you how data can be passed to subprograms by using parameters. But there are really two kinds of parameters:

  • Formal parameters are variables that you define in the declaration part of the subprogram (for example, variables i_rad1_nr and i_rad2_nr are formal parameters of the function F_GetDiff_NR from Listing A Function Example ). These are the only elements of the subprogram visible to the outside world.

  • Actual parameters are what you pass from the main program into the subprogram. (In Listing Stopping Procedure Execution , you passed literals 3, 4, 5, and 6 to the function F_GetDiff_NR, so these were actual parameters of that function.) Depending upon the type of formal parameter, actual parameters could be literals, variables, expressions, and so on. If you have more than one layer of subprogram, the formal parameter on a higher level could be an actual parameter of the lower one (for example, variable i_rad1_nr is an actual parameter of function f_getArea_Nr and a formal parameter of function f_getDiff_Nr).

If possible, Oracle dynamically converts datatypes of actual parameters to match formal parameters.


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