Functions vs. Procedures in PL/SQL: What's the Key Difference?

Distinguishing Functions from Procedures in PL/SQL

When working with PL/SQL, understanding the fundamental differences between functions and procedures is crucial. While both are used for enhancing code reusability, they vary significantly in their primary purpose.

Procedures: No Explicit Return Value

A procedure doesn't explicitly return a value. Its primary function is to execute a series of SQL statements, update variables, or perform other operations without returning any specific data.

Functions: Explicit Return Value

In contrast, a function has an explicit return value. It calculates and returns a single value, which can be used in expressions, assignments, or passed as parameters to other functions or procedures.

Return Clause

To define a function, you use the "CREATE OR REPLACE FUNCTION" syntax, followed by a return clause between the parameter list and the "as" keyword. The return clause indicates the data type of the value that the function will return.

Last Statement Return

Within the function body, the last statement must include a "return" keyword followed by the value to be returned. This value must match the data type specified in the return clause.

Example

Consider the following example:

CREATE OR REPLACE PROCEDURE my_proc (p_name IN VARCHAR2 := 'John') AS
BEGIN
   -- Code to update a record or perform other operations
   ...
END;

CREATE OR REPLACE FUNCTION my_func (p_name IN VARCHAR2 := 'John')
RETURN VARCHAR2 AS
BEGIN
   -- Calculations to compute a VARCHAR2 variable
   ...
   RETURN my_varchar2_local_variable;
END;

In this example, "my_proc" is a procedure that doesn't return any explicit value, while "my_func" is a function that returns a VARCHAR2 value.

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