PL/SQL - column value is updated as 0 instead of numeric value - plsql

Question

Declare
v_cnt varchar2(20);
v_cnd varchar2(20);
v_total varchar2(20);
begin
select count(emp_id) into v_cnt from emp1;
select count(emp_id) into v_cnd from emp2;
v_total:=v_cnt+v_cnd;
dbms_output.put_line('before');
dbms_output.put_line(v_total);
update emp3 set total_emp=v_total where dept_no=40;
commit;
dbms_output.put_line('after');
dbms_output.put_line(v_total);
end;
In the above program, value for the column total_emp is getting updated as 0 instead of numeric value.
However, when I use dbms_output statement to print the value, for both the cases, before and after , I'm getting the numeric value for the variable v_total.
v_total value is not getting updated to column value in table.
table column definition for total_emp is varchar2(20).
Also, I tried to hard code value for total_emp column in the above statement and it worked.
So, the problem is variable value when used in the update statement it's not getting updated to column.
Please help me.

Answer 1

The variables you declared should be of type NUMBER instead of VARCHAR2, as you intend to use them in calculations. I also suggest you add an exception handler to report any errors which may occur. It's also a good idea to show how many rows were affected by your update. You might want to rewrite your code as:
Declare
v_cnt NUMBER;
v_cnd NUMBER;
v_total NUMBER;
begin
select count(emp_id)
into v_cnt
from emp1;
select count(emp_id)
into v_cnd
from emp2;
v_total:=v_cnt+v_cnd;
dbms_output.put_line('before');
dbms_output.put_line(v_total);
update emp3
set total_emp=v_total
where dept_no=40;
DBMS_OUTPUT.PUT_LINE('Number of rows updated=' || SQL%ROWCOUNT);
commit;
dbms_output.put_line('after');
dbms_output.put_line(v_total);
EXCEPTION
WHEN OTHERS THEN
DBMS_OUTPUT.PUT_LINE('Exception: ' || SQLCODE || ' ' || SQLERRM);
ROLLBACK;
end;
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