Re: Thread_overrun error

[Rick James]

> UPDATE jaces_fieldmark SET debt_amount=balance;

Is jaces_fieldmark a temporary table whose sole purpose is to hold debt_amount?
If so, use a variable instead: @debt_amount.

I still don't see what you are trying to accomplish. Please study this to see if it is related:

SELECT
@balance := @balance + amount AS running_sum,
FROM ( SELECT @balance := 0 )
JOIN MyTbl
WHERE ...
ORDER BY ...

It calculates a "running sum" of the column `amount`.
It does it _without_ a cursor.
The subquery is to initialize @balance without having to issue a second SELECT or SET. (This is a minor issue.)

Rule of Thumb: Cursors can usually be turned into single statements. Always try to do so. The code will run much faster; the code will (ultimately) be simpler.