How to add salary from two tables in stored procedure - mysql

Question

I want to add the salary from two tables in stored procedure on the basis of id column:
DDl:
create table salary1 (id varchar(20), salary varchar(20));
create table salary2 (id varchar(20), salary varchar(20));
DML:
insert into salary1 values('1', '100');
insert into salary1 values('2', '200');
insert into salary2 values('1', '10');
insert into salary2 values('2', '10');
Database: mysql
Output should like this:
id total_sal
1 110
2 210
My stored procedure look like:
CREATE PROCEDURE totalSal()
BEGIN
DECLARE tbl1_id varchar(30);
DECLARE tbl1_sal varchar(30);
DECLARE tbl2_id varchar(30);
DECLARE tbl2_sal varchar(30);
DECLARE total_sal varchar(30);
DECLARE c1 CURSOR FOR SELECT * FROM salary1;
DECLARE c2 CURSOR FOR SELECT * FROM salary2;
-- Open first cursor
OPEN c1;
LOOP
FETCH c1 INTO tbl1_id, tbl1_sal;
-- Open second cursor
OPEN c2;
LOOP
FETCH c2 INTO tbl2_id, tbl2_sal;
IF tbl1_id = tbl2_id THEN
set total_sal := tbl1_sal + tbl2_sal;
ELSE
set total_sal := tbl_sal;
END IF;
END LOOP;
CLOSE c2;
END LOOP;
CLOSE c1;
end $$
It got's successfully compiled, but when i am running the procedure i am getting the below error:
ERROR 1329 (02000): No data - zero rows fetched, selected, or processed
I have also used the DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1; in my procedure. but still my problem is unresolved.
If someone can solve this problem in oracle, that would also help me.
Note : I cannot perform join operation on these tables. Because of a few performance issues.
Thanks in advance !!!

Answer 1

Solution 1:
Using collection and only one iteration of 2 loop
You should consider to fix your performance issue on join. Performing loop is slower than a set base approach in most case.
If I follow your logic, what you realy want is to loop trough all the salary2 table for each salary1 row in order to found the right ID => millions of loop.
You can consider doing 2 separated loop and store data inside and indexed array. ( the key will be the tlb1_id).
If the key exist : sum the salary values, if not exist insert it inside the array.
At the end of the procedure, just select the array as table.
Solution 2:
Using a join on integer indexed columns
you can add a new integer column on each table
Populate this column with the casted value of the ID column
Add an index on these columns on each tables
After that you will be able to perform a join
Have a look at this fiddle http://sqlfiddle.com/#!9/c445de/1 , it can be time consuming to perform theses step and disk space consumuming to add a new columns and indexes but the join operation may be faster than before.

Answer 2

You can do something like this... I have moved the second cursor inside the loop so that it only goes over the id's from table 1. This should help the logic for the procedure but still I would recommend trying to figure out how to fix the join to get the results as that seems like an easier way and should be much faster if done correctly.
CREATE PROCEDURE totalSal()
BEGIN
DECLARE tbl1_id varchar(30);
DECLARE tbl1_sal varchar(30);
DECLARE tbl2_id varchar(30);
DECLARE tbl2_sal varchar(30);
DECLARE total_sal varchar(30);
DECLARE c1 CURSOR FOR SELECT * FROM salary1;
-- Open first cursor
OPEN c1;
LOOP
FETCH c1 INTO tbl1_id, tbl1_sal;
SELECT COUNT(*) INTO v_rowcount FROM salary2 WHERE id = tbl1_id;
IF v_rowcount > 0 THEN
Begin
DECLARE c2 CURSOR FOR SELECT * FROM salary2 WHERE id = tbl1_id;
-- Open second cursor
OPEN c2;
LOOP
FETCH c2 INTO tbl2_id, tbl2_sal;
IF tbl1_id = tbl2_id THEN
set total_sal := tbl1_sal + tbl2_sal;
ELSE
set total_sal := tbl_sal;
END IF;
END LOOP;
CLOSE c2;
END IF;
END
END LOOP;
CLOSE c1;
end $$

Answer 3

Well you asked for an answer without JOIN, but that seemed arbitrary, so here's an answer with JOIN.
SELECT
sums1.id
, S1Sum + S2Sum AS SalarySum
FROM (SELECT id, SUM(CAST(salary AS int)) AS S1Sum
FROM salary1
GROUP BY id) sums1
JOIN (SELECT id, SUM(CAST(salary AS int)) AS S2Sum
FROM salary2
GROUP BY id) sums2
ON sums1.id = sums2.id
I am guessing your performance is bad because all of your columns are varchar when they should be int or numeric. But we don't have much to go on so hopefully this helps you come to a solid solution.
Also the post was edited to add both MySQL and Oracle tags so it's difficult to determine what the syntax should be...