Question

My Table is like

CREATE TABLE IF NOT EXISTS `pricerange` (
  `priceRangeID` int(11) NOT NULL AUTO_INCREMENT,
  `catID` int(11) NOT NULL,
  `Below 500` tinyint(1) NOT NULL DEFAULT '0',
  `501-1000` tinyint(1) NOT NULL DEFAULT '0',
  `1001-2000` tinyint(1) NOT NULL DEFAULT '0',
  `2001-3000` tinyint(1) NOT NULL DEFAULT '0',
  `3001-4000` tinyint(1) NOT NULL DEFAULT '0',
  `4001-5000` tinyint(1) NOT NULL DEFAULT '0',
  `5001-6000` tinyint(1) NOT NULL DEFAULT '0',
  `6001-7000` tinyint(1) NOT NULL DEFAULT '0',
  `7001-8000` tinyint(1) NOT NULL DEFAULT '0',
  `8001-9000` tinyint(1) NOT NULL DEFAULT '0',
  `9001-10000` tinyint(1) NOT NULL DEFAULT '0',
  `10001-100000` tinyint(1) NOT NULL DEFAULT '0',
  `above 100000` tinyint(1) NOT NULL DEFAULT '0',
  PRIMARY KEY (`priceRangeID`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=2 ;

INSERT INTO `pricerange` (`priceRangeID`, `catID`, `Below 500`, `501-1000`, `1001-2000`, `2001-3000`, `3001-4000`, `4001-5000`, `5001-6000`, `6001-7000`, `7001-8000`, `8001-9000`, `9001-10000`, `10001-100000`, `above 100000`) VALUES
(1, 3, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1, 1);

Here i want to extract the field name having values 1 for a given catID. Can any one help me how to write this query in mysql?

I have tried SHOW FIELDS from pricerange but it shows all field names with its details its not dealing with values, SELECT * from pricerange but it needs some php manipulations. But i want to write it in MYSQL only.

Answer 1

The key to solving this problem is to use the information_schema

Here is the query for you:

SELECT A.column_name FROM
(select ordinal_position-3 pos,column_name from information_schema.columns
where table_name='pricerange' and LOCATE('-',column_name)) A
INNER JOIN
(SELECT CONCAT(`501-1000`,`1001-2000`,`2001-3000`,
`3001-4000`,`4001-5000`,`5001-6000`,`6001-7000`,
`7001-8000`,`8001-9000`,`9001-10000`,
`10001-100000`) bitmap FROM pricerange) B
ON SUBSTR(bitmap,pos,1) = '1';

I loaded your data

mysql> DROP DATABASE IF EXISTS sumant;
Query OK, 1 row affected (0.06 sec)
mysql> CREATE DATABASE sumant;
Query OK, 1 row affected (0.00 sec)
mysql> USE sumant
Database changed
mysql> CREATE TABLE IF NOT EXISTS `pricerange` (
    ->   `priceRangeID` int(11) NOT NULL AUTO_INCREMENT,
    ->   `catID` int(11) NOT NULL,
    ->   `Below 500` tinyint(1) NOT NULL DEFAULT '0',
    ->   `501-1000` tinyint(1) NOT NULL DEFAULT '0',
    ->   `1001-2000` tinyint(1) NOT NULL DEFAULT '0',
    ->   `2001-3000` tinyint(1) NOT NULL DEFAULT '0',
    ->   `3001-4000` tinyint(1) NOT NULL DEFAULT '0',
    ->   `4001-5000` tinyint(1) NOT NULL DEFAULT '0',
    ->   `5001-6000` tinyint(1) NOT NULL DEFAULT '0',
    ->   `6001-7000` tinyint(1) NOT NULL DEFAULT '0',
    ->   `7001-8000` tinyint(1) NOT NULL DEFAULT '0',
    ->   `8001-9000` tinyint(1) NOT NULL DEFAULT '0',
    ->   `9001-10000` tinyint(1) NOT NULL DEFAULT '0',
    ->   `10001-100000` tinyint(1) NOT NULL DEFAULT '0',
    ->   `above 100000` tinyint(1) NOT NULL DEFAULT '0',
    ->   PRIMARY KEY (`priceRangeID`)
    -> ) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=2 ;
Query OK, 0 rows affected (0.17 sec)

mysql> INSERT INTO `pricerange` (`priceRangeID`, `catID`, `Below 500`, `501-1000`, `1001-2000`, `2001-3000`, `3001-4000`, `4001-5000`, `5001-6000`, `6001-7000`, `7001-8000`, `8001-9000`, `9001-10000`, `10001-100000`, `above 100000`) VALUES
    -> (1, 3, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1, 1);
Query OK, 1 row affected (0.07 sec)

mysql>

Here is the query executed:

mysql> SELECT A.column_name FROM
    -> (select ordinal_position-3 pos,column_name from information_schema.columns
    -> where table_name='pricerange' and LOCATE('-',column_name)) A
    -> INNER JOIN
    -> (SELECT CONCAT(`501-1000`,`1001-2000`,`2001-3000`,
    -> `3001-4000`,`4001-5000`,`5001-6000`,`6001-7000`,
    -> `7001-8000`,`8001-9000`,`9001-10000`,
    -> `10001-100000`) bitmap FROM pricerange) B
    -> ON SUBSTR(bitmap,pos,1) = '1';
+--------------+
| column_name  |
+--------------+
| 5001-6000    |
| 6001-7000    |
| 9001-10000   |
| 10001-100000 |
+--------------+
4 rows in set (0.02 sec)

mysql>

It also works in reverse. Here is the same query but hunting down only zeros:

mysql> SELECT A.column_name FROM
    -> (select ordinal_position-3 pos,column_name from information_schema.columns
    -> where table_name='pricerange' and LOCATE('-',column_name)) A
    -> INNER JOIN
    -> (SELECT CONCAT(`501-1000`,`1001-2000`,`2001-3000`,
    -> `3001-4000`,`4001-5000`,`5001-6000`,`6001-7000`,
    -> `7001-8000`,`8001-9000`,`9001-10000`,
    -> `10001-100000`) bitmap FROM pricerange) B
    -> ON SUBSTR(bitmap,pos,1) = '0';
+-------------+
| column_name |
+-------------+
| 501-1000    |
| 1001-2000   |
| 2001-3000   |
| 3001-4000   |
| 4001-5000   |
| 7001-8000   |
| 8001-9000   |
+-------------+
7 rows in set (0.01 sec)

mysql>

Give it a Try !!!