PL/SQL Defining the select statement for sum in If and loop - sql

Question

For an example, we have employer salary and department based in emp table.
In SQL , we can retrieve the total salary per department just by doing this
SELECT SUM(SAL) FROM EMP WHERE DEPTNO = 20 ; //Lets put it we finding sum for dept 20.
But where else for pl/sql , I think I am syntactically wrong . I am using cursor to store all the datas. in my if statement which is inside a loop below , I tried my logic with
if deptno = 20 THEN
totalSalary = sum(salary);
DBMS_OUTPUT.PUT_LINE('Department : 20' || total Salary);
This is my actual code .
DECLARE
msal emp.salary%TYPE;
mdept emp.departmentNo%TYPE;
new_salary number(10,2);
CURSOR E1 IS select salary , departmentNo from emp;
BEGIN
OPEN E1;
LOOP
FETCH E1 into msal , mdeptno;
IF mdeptno = 20 THEN
---- I cant seems to find the right logic here to print out the total sum for department 20---
END IF;
EXIT WHEN E1%NOTFOUND;
END LOOP;
CLOSE E1;
END;
/
Thanks in advance

Answer 1

There is no need to use PL/SQL for thing which you can do with SQL. But if you are really need it, use following:
DECLARE
msal emp.salary%TYPE;
mdept emp.departmentNo%TYPE;
new_salary number(10,2);
CURSOR E1 (p_dept number) IS
select sum(salary) from emp where departmentNo = p_dept;
BEGIN
OPEN E1(20);
FETCH E1 into msal;
dbms_output.put_line(msal);
CLOSE E1;
END;
/

Answer 2

You can introduce another variable for sum aggregation and in each loop iteration add it up.
And then print out once required.
DECLARE
msal emp.salary%TYPE;
mdept emp.departmentNo%TYPE;
sum_salary number(10,2) := 0;
CURSOR E1 IS select salary , departmentNo from emp;
BEGIN
OPEN E1;
LOOP
FETCH E1 into msal , mdeptno;
sum_salary := sum_salary + msal;
IF mdeptno = 20 THEN
dbms_output.put_line(sum_salary);
EXIT WHEN E1%NOTFOUND;
END LOOP;
CLOSE E1;
PL/SQL allows you to access row by row, ( that is done by SQL behind the scenes for you)

Answer 3

Keep a running total with the variable, totalSalary
The algorithm is as follows:
-fetch values from cursor, e1, and assign to msal and mdeptno
-for each fetched value of msal (within the loop), keep a running total using the variable, tot_sal (or totalSalary as you originally posted)
With your approach, the assignment,totalSalary := sum(salary);, does nothing but throws errors because salary is not defined as a variable. The cursor fetches the value of salary (mine is sal) and it is assigned to msal.
If the assignment was totalSalary := sum(msal);, then it would writes over the previous fetched value and does not keep track of a running total.
The standard way to do this is initialize tot_sal to zero (or totalSalary) before the loop and then keep a running total for each fetched record:
tot_sal := tot_sal + msal;
Here is the simple sql result juxtaposed with the anonymous block:
SCOTT#dev>SELECT
2 SUM(sal)
3 FROM
4 emp
5 WHERE
6 deptno = 20;
SUM(SAL)
10875
SCOTT#dev>DECLARE
2 msal emp.sal%TYPE;
3 mdeptno emp.deptno%TYPE;
4 tot_sal emp.sal%TYPE;
5 CURSOR e1 IS
6 SELECT
7 sal,
8 deptno
9 FROM
10 emp;
11
12 BEGIN
13 tot_sal := 0;
14 OPEN e1;
15 LOOP
16 FETCH e1 INTO msal,mdeptno;
17 IF
18 mdeptno = 20
19 THEN
20 tot_sal := tot_sal + msal;
21 END IF;
22
23 EXIT WHEN e1%notfound;
24 END LOOP;
25
26 CLOSE e1;
27 dbms_output.put_line(tot_sal);
28 END;
29 /
10875
PL/SQL procedure successfully completed.

Answer 4

thank you for all your response ,
I am assigned to do this in pl/sql ,
i appreciate all the response from you guys. I have come out with the easiest technique in getting the result for sum, min and max and avg.
What i basically did was using the inbuild function that was already in sql and implement it in my select statement . So i have solve it by
DECLARE
totalSal emp.salary%TYPE;
maxSal emp.salary%TYPE;
minSal emp.salary%TYPE;
mdept emp.departmentNo%TYPE := 20; /* for an example getting all values for dept 20 */
CURSOR E1 IS select sum(salary) , max(salary) , min(sal) from emp where
departmentNo = mdept group by departmentNo;
BEGIN
OPEN E1;
LOOP
FETCH E1 into totalSal , maxSal , minSal;
EXIT WHEN E1%NOTFOUND;
DBMS_OUTPUT.PUT_LINE('...' || maxsal); /*...so on for display*/
END LOOP;
CLOSE E1;
END; /