How to do a sum of previous row value with the current row and display the result in another row with MySQL cross join?
Let us first create a table −
mysql> create table DemoTable(Value int);
Query OK, 0 rows affected (1.79 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable values(50);
Query OK, 1 row affected (0.24 sec)
mysql> insert into DemoTable values(20);
Query OK, 1 row affected (0.68 sec)
mysql> insert into DemoTable values(30);
Query OK, 1 row affected (0.18 sec)
Display all records from the table using select statement −
mysql> select *from DemoTable;
This will produce the following output −
+-------+
| Value |
+-------+
| 50 |
| 20 |
| 30 |
+-------+
3 rows in set (0.00 sec)
Here is the query to do a sum of previous rows in MySQL a sum of previous rows −
mysql> select t.Value,
(@s := @s + t.Value) as Number
from DemoTable t cross join
(select @s := 0) p
order by t.Value;
This will produce the following output −
+-------+--------+
| Value | Number |
+-------+--------+
| 20 | 20 |
| 30 | 50 |
| 50 | 100 |
+-------+--------+
3 rows in set (0.07 sec)
Published on 03-Sep-2019 15:50:14
