how to calculate balance with previous value.

Consider this example, which uses a non-temporary table... 

DROP TABLE IF EXISTS temp;

CREATE TABLE temp
(slno INT NOT NULL AUTO_INCREMENT PRIMARY KEY
,debit INT null
,credit INT null
);


INSERT INTO temp VALUES
(1,10,0),
(2,0,40),
(3,50,0),
(4,0,10),
(5,0,10);

SELECT * FROM temp;
+------+-------+--------+
| slno | debit | credit |
+------+-------+--------+
|    1 |    10 |      0 |
|    2 |     0 |     40 |
|    3 |    50 |      0 |
|    4 |     0 |     10 |
|    5 |     0 |     10 |
+------+-------+--------+

SELECT x.slno
     , x.debit
     , x.credit
     , SUM(y.bal) balance 
  FROM
     ( 
       SELECT *,debit-credit bal FROM temp
     ) x
  JOIN
     ( 
       SELECT *,debit-credit bal FROM temp
     ) y
    ON y.slno <= x.slno
 GROUP 
    BY x.slno;

+------+-------+--------+---------+
| slno | debit | credit | balance |
+------+-------+--------+---------+
|    1 |    10 |      0 |      10 |
|    2 |     0 |     40 |     -30 |
|    3 |    50 |      0 |      20 |
|    4 |     0 |     10 |      10 |
|    5 |     0 |     10 |       0 |
+------+-------+--------+---------+

Note, my balance differs from yours - but I assume that's because you made a mistake!?!

Source