Add previous value of one column to present value of another column and get result column

Question

I have a table like this

I want to replace null values in P by logic

present value of column P =  present value of column S + previous value of column P.

Expected output:

Thanks in advance

I think the first column to be populated should be `P` then you can update `R` — Ergest Basha, Dec 03 '21 at 16:23
What sorting expression provides shown rows ordering? how to determine what row is "next row"? — Akina, Dec 03 '21 at 18:42
@ErgestBasha I have edited question. Could you please look into this? — Ashok Anumula, Dec 04 '21 at 09:08
Your edition changes nothing. *how to determine what row is "next row"?* - your edition does not answer. — Akina, Dec 04 '21 at 18:24
@AshokAnumula I think you need to add first an id autoincrement to determine the row sort as @Akina mentioned. Use: `ALTER TABLE your_table ADD id INT PRIMARY KEY AUTO_INCREMENT FIRST ;` — Ergest Basha, Dec 04 '21 at 20:13
Does this answer your question? [Create a Cumulative Sum Column in MySQL](https://stackoverflow.com/questions/2563918/create-a-cumulative-sum-column-in-mysql) — Progman, Dec 05 '21 at 10:57

score 0 · Accepted Answer · answered Dec 06 '21 at 10:06

0

We can achieve this by using variables in mysql

SELECT 
    pur.Id, pur.s,
    (@b := @b + pur.s) - 10 AS p
FROM
    (SELECT @b := 0.0) AS dummy 
  CROSS JOIN
    purchase AS pur
ORDER BY
    Id ;

answered Dec 06 '21 at 10:06

Ashok Anumula

1 Answers1