Question

I need to create a view for with resulting math function multiply. Is this possible?

Table:

mysql> show create table devices \G
Create Table: CREATE TABLE `devices` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `d_type` varchar(255) NOT NULL,
  `multiplier` char(255) NOT NULL DEFAULT '',
  `value` decimal(10,3) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=latin1
1 row in set (0.00 sec)

Sample rows:

mysql> SELECT devices.id, devices.d_type, devices.multiplier, devices.`value`  FROM devices;   
+----+--------------------------+------------+--------+
| id | d_type                   | multiplier | value  |
+----+--------------------------+------------+--------+
|  1 | Cisco Call Manager       | /          |  4.000 |
|  2 | Generic Router/Switch    | *          |  0.350 |

I need to somehow calculate using the multiplier to provide a result for various math.
Example (not working of course):

SELECT devices.id, devices.d_type, devices.multiplier, devices.`value`, (SELECT 1 $multiplier devices.`value`) as EPS FROM devices; 

The result in this case should be:

+----+--------------------------+------------+--------+--------+
| id | d_type                   | multiplier | value  |   EPS  |
+----+--------------------------+------------+--------+--------+
|  1 | Cisco Call Manager       | /          |  4.000 |  0.25  |
|  2 | Generic Router/Switch    | *          |  0.350 |  0.35  |

we need to derive the EPS column by dividing or multiplying 1 by the value column.
Is there a way to use that multiplier as a determination of whether to divide or multiply?

(note that I used 1 as an example, this could be any incoming integer from user input)

Answer 1

You can use this query

SELECT devices.id, devices.d_type, devices.multiplier, devices.`value`, IF(multiplier = '/', 1/value, 1*value) as EPS FROM devices;

it works for you.