How to create a Cumulative Sum Column in MySQL?

To create a cumulative sum column in MySQL, you need to create a variable and set to value to 0. Cumulative sum increments the next value step by step with current value.

Firstly, you need to create a variable with the help of SET. The syntax is as follows −

set @anyVariableName:= 0;

The syntax to create a cumulative sum column in MySQL is as follows −

select yourColumnName1,yourColumnName2,........N,(@anyVariableName := @anyVariableName + yourColumnName2) as anyVariableName
from yourTableName order by yourColumnName1;

To understand the above concept, let us create a table. The following is the query to create a table −

mysql> create table CumulativeSumDemo
   −> (
   −> BookId int,
   −> BookPrice int
   −> );
Query OK, 0 rows affected (0.67 sec)

Insert some records in the table with the help of select statement. The query to insert record is as follows −

mysql> insert into CumulativeSumDemo values(101,400);
Query OK, 1 row affected (0.15 sec)

mysql> insert into CumulativeSumDemo values(102,500);
Query OK, 1 row affected (0.16 sec)

mysql> insert into CumulativeSumDemo values(103,600);
Query OK, 1 row affected (0.16 sec)

mysql> insert into CumulativeSumDemo values(104,1000);
Query OK, 1 row affected (0.18 sec)

Display all records which I have inserted with the help of insert command. The query is as follows −

mysql> select *from CumulativeSumDemo;

The following is the output −

+--------+-----------+
| BookId | BookPrice |
+--------+-----------+
|    101 |       400 |
|    102 |       500 |
|    103 |       600 |
|    104 |      1000 |
+--------+-----------+
4 rows in set (0.00 sec)

To add cumulative sum column, first you need to create a variable. The query is as follows −

mysql> set @CumulativeSum := 0;
Query OK, 0 rows affected (0.00 sec)

Implement the above syntax discussed in the beginning to add a cumulative sum column. The query is as follows −

mysql> select BookId,BookPrice,(@CumulativeSum := @CumulativeSum + BookPrice) as CumSum
   −> from CumulativeSumDemo order by BookId;

The following is the output. Here the cumulative sum column is also visible −

+--------+-----------+--------+
| BookId | BookPrice | CumSum |
+--------+-----------+--------+
|    101 |       400 |    400 |
|    102 |       500 |    900 |
|    103 |       600 |   1500 |
|    104 |      1000 |   2500 |
+--------+-----------+--------+
4 rows in set (0.00 sec)