Question

I have a table with a credit and debit column.

I need to get the highest balance out of that, and I think a stored procedure is the way to do it, but I have no idea how.

I need to start with the first row, add the debits, subtract the credits and store the value A.

Second row is A+debit-credit=B; A = max(A,B) Repeat last step till the end.

Remember, I’m looking for the highest EVER, not the current, which would just be sum(debit-credit)

Answer 1

It seems to me that you’d want the running total to be A+credit-debit but switch them if needed.

SET @balance := 0; SET @high := 0; SELECT @high := GREATEST(@balance := @balance+credit-debit, @high) FROM mytable; SELECT @high; 

edit: In response to your comment about forming a stored function from this… unlike stored procedures, stored functions must return one value, so they can’t contain a SELECT query unless the query stores its result in a variable. This means the query must be guaranteed to have a single-value result. Below is a function I got to work, because in this case you only want the MAX value of @high anyway:

CREATE FUNCTION high_bal() RETURNS DECIMAL BEGIN   SET @balance := 0;   SET @high := 0;    SELECT MAX(@high := GREATEST(@balance := @balance+debit_acc-credit_acc, @high))   INTO @high   FROM credit_acc where credit_used_acc=63395;    RETURN @high; END$$