Multiply values of two columns and display it a new column in MySQL?

Let us first create a table −

mysql> create table DemoTable
   -> (
   -> NumberOfItems int,
   -> Amount int
   -> );
Query OK, 0 rows affected (0.57 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable values(4,902);
Query OK, 1 row affected (0.45 sec)

mysql> insert into DemoTable values(5,1000);
Query OK, 1 row affected (0.16 sec)

mysql> insert into DemoTable values(3,80);
Query OK, 1 row affected (0.12 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable;

Output

+---------------+--------+
| NumberOfItems | Amount |
+---------------+--------+
|             4 | 902    |
|             5 | 1000   |
|             3 | 80     |
+---------------+--------+
3 rows in set (0.00 sec)

Following is the query for database manipulation −

mysql> select NumberOfItems,Amount,(NumberOfItems*Amount) AS PayableAmount from DemoTable;

Output

+---------------+--------+---------------+
| NumberOfItems | Amount | PayableAmount |
+---------------+--------+---------------+
|             4 | 902    |         3608  |
|             5 | 1000   |         5000  |
|             3 | 80     |         240   |
+---------------+--------+---------------+
3 rows in set (0.00 sec)