MySQL query to calculate the total amount from column values with Cost and Quantity?

Let us first create a table −

mysql> create table DemoTable
(
   Cost int,
   Quantity int
);
Query OK, 0 rows affected (0.80 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable values(65,2);
Query OK, 1 row affected (0.08 sec)
mysql> insert into DemoTable values(290,4);
Query OK, 1 row affected (0.18 sec)
mysql> insert into DemoTable values(40,3);
Query OK, 1 row affected (0.10 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable;

This will produce the following output −

+------+----------+
| Cost | Quantity |
+------+----------+
| 65   |        2 |
| 290  |        4 |
| 40   |        3 |
+------+----------+
3 rows in set (0.00 sec)

Following is the query to calculate the total amount −

mysql> select Cost,Quantity,Cost*Quantity AS Total_Amount from DemoTable;

This will produce the following output −

+------+----------+--------------+
| Cost | Quantity | Total_Amount |
+------+----------+--------------+
|   65 |        2 |          130 |
|  290 |        4 |         1160 |
|   40 |        3 |          120 |
+------+----------+--------------+
3 rows in set (0.02 sec)