MySQL SELECT to sum a column value with previous value

For this, you can use a session variable. Let us first create a table −

mysql> create table DemoTable809(Price int);
Query OK, 0 rows affected (0.53 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable809 values(40);
Query OK, 1 row affected (0.17 sec)
mysql> insert into DemoTable809 values(50);
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable809 values(60);
Query OK, 1 row affected (0.12 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable809;

This will produce the following output −

+-------+
| Price |
+-------+
|    40 |
|    50 |
|    60 |
+-------+
3 rows in set (0.00 sec)

Following is the query to sum a column value with a previous value −

mysql> select @currentSum:=@currentSum+Price from DemoTable809;

This will produce the following output −

+--------------------------------+
| @currentSum:=@currentSum+Price |
+--------------------------------+
|                             40 |
|                             90 |
|                            150 |
+--------------------------------+
3 rows in set (0.00 sec)