PL/SQL exceptions dont raise - exception

Question

I'm new to PL/SQL and I've been struggling with this problem waay too long so I thought I'll ask here:
What I want to achieve:
I want to insert a new employee into my 'emp' table using pl/sql
blocks.
I want the data to be input from the keyboard.
Then check if the data is correct using exceptions.
After that I want the user to confirm it writing 'yes' or 'no'.
What doesn't work:
Exceptions are not being raised even though I input invalid data.
As it is now it asks the user to confirm at the same time as asking for the data. I want it to ask after inputing and after checking the
correctness
My code:
DECLARE
empno NUMBER;
ename Varchar2(30);
job Varchar2(30);
mgr NUMBER;
hiredate DATE;
sal NUMBER;
comm NUMBER;
deptno NUMBER;
confirm VARCHAR2(3);
negative_number EXCEPTION;
invalid_date EXCEPTION;
BEGIN
INSERT INTO emp
VALUES (&empno, '&ename', '&job', &mgr, '&hiredate', &sal, &comm, &deptno);
IF empno < 0 OR mgr < 0 OR sal < 0 OR comm < 0 OR deptno < 0 THEN
RAISE negative_number;
ELSIF hiredate > SYSDATE THEN
RAISE invalid_date;
END IF;
IF '&confirm' = 'yes' THEN commit;
ELSE rollback;
END IF;
EXCEPTION
WHEN negative_number THEN
dbms_output.put_line('number cannot be negative');
WHEN invalid_date THEN
dbms_output.put_line('cannot be future date');
END;

Answer 1

Just a little modification to your present code:
DECLARE
empno NUMBER := &empno;
ename Varchar2(30) := '&ename';
job Varchar2(30) := '&job';
mgr NUMBER := &mgr;
hiredate DATE := TO_DATE('&hiredate', 'mm/dd/yyyy');
sal NUMBER := &sal;
comm NUMBER := &comm;
deptno NUMBER := &deptno;
confirm VARCHAR2(3);
BEGIN
INSERT INTO emp
VALUES (empno, ename, job, mgr, hiredate, sal, comm, deptno);
IF empno < 0 OR mgr < 0 OR sal < 0 OR comm < 0 OR deptno < 0 THEN
RAISE_APPLICATION_ERROR ('-20001', 'Number cannot be negative!');
ELSIF hiredate > SYSDATE THEN
RAISE_APPLICATION_ERROR ('-20002', 'Cannot be future date!');
END IF;
confirm := '&confirm';
IF lower(confirm) IN ('yes', 'y') THEN
commit;
ELSE
rollback;
END IF;
END;
The last part - confirm is not possible using pure PL/SQL though. What the code does is get the value of confirm at the beginning of the execution itself, along with other variables. What you should do for this is build a front-end that would control the flow of your program before issuing a DML.

Answer 2

DECLARE
empno NUMBER := 10;
ename Varchar2(30) := 'sinha';
job Varchar2(30) := 'ITTTT';
mgr NUMBER := 100;
hiredate DATE := TO_DATE('09/09/2014', 'mm/dd/yyyy');
sal NUMBER := 2000;
comm NUMBER := 50;
deptno NUMBER := 10;
invalid_emp exception;
invalid_date exception;
BEGIN
INSERT INTO empl
VALUES (empno, ename, job, mgr, hiredate, sal, comm, deptno);
IF empno < 0 OR mgr < 0 OR sal < 0 OR comm < 0 OR deptno < 0 THEN
RAISE invalid_emp;
ELSIF hiredate > SYSDATE THEN
RAISE invalid_date;
END IF;
exception
when invalid_emp then
dbms_output.put_line('number cannot be negative');
when invalid_date then
dbms_output.put_line('cannot be future date');
END;
this is how you can use a user defined exception as you wanted