Can we call procedure inside function in oracle PL/SQL? If not then why? - sql

Question

In some places I heard that we cannot call procedure inside function in oracle PL/SQL. May I know why is it so?
Also why cant we call a procedure within a SELECT statement whereas we can call a function in the same SELECT statement.

Answer 1

Yes you can call a procedure from a function in Oracle PL/SQL.
You can't call a procedure from a SELECT statement because it doesn't return a value. A function can be called from a SELECT because it does:
select empno, calc_salary_function(empno) salary
from emp;
Calling a procedure from a SELECT makes no sense really:
select empno, fire_employee(empno) -- Will fail
from emp;
What would you expect to see in the second column of the results?

Answer 2

Procedure is not used to return a value. Procedures performs group of operations to achieve a task, where as function is used to return a value.
Procedure is executed as an operation, function can be used in the select statement derive a value

Answer 3

you can call procedure from function.
create table test(a varchar2(30));
create or replace procedure pro_insert_values
as
begin
insert into test values('anything');
end;
create or replace function fn_get_data
return number
as
begin
pro_insert_values;
return 1;
end;
sql>variable x number
exec :x:=fn_get_data

Answer 4

You can use below code to validate that procedure can be called from inside function.
create table country_name(id number, country varchar2(100));
insert all
into country_name values(1, 'INDIA')
into country_name values(2, 'UK')
SELECT * FROM DUAL;
/
CREATE OR REPLACE FUNCTION COUNTRY_FOUND_NOTFOUND(V_NAME VARCHAR2)
RETURN VARCHAR2
AS
V_COUNTRY VARCHAR2(100);
BEGIN
BEGIN
SELECT COUNTRY INTO V_COUNTRY FROM country_name WHERE COUNTRY = V_NAME;
RETURN 'FOUND';
EXCEPTION
WHEN NO_DATA_FOUND THEN
INSERT_COUNTRY(V_NAME);
RETURN 'NOT FOUND';
END;
RETURN 'NOT FOUND';
END;
/
CREATE OR REPLACE PROCEDURE INSERT_COUNTRY(V_NAME IN VARCHAR2)
AS
V_ID NUMBER;
BEGIN
SELECT MAX(ID) INTO V_ID FROM COUNTRY_NAME;
INSERT INTO COUNTRY_NAME VALUES(V_ID+1, V_NAME);
END;
/
SET SERVEROUTPUT ON;
DECLARE
V_NAME VARCHAR2(100);
BEGIN
V_NAME := COUNTRY_FOUND_NOTFOUND('SPAIN');
DBMS_OUTPUT.PUT_LINE(V_NAME);
END;