php retrieve multiple data from mysql - php

Question

I insert multiple id from my checkbox to MySQL database using php post form. In example I insert id (checkbox value table test) to mysql. Now I need a function to retrieve data from MySQL and print to my page with my example output (print horizontal list name of table test where data = userid)
My checkbox value (table name is test):
id | name
----+-------
1 | test1
2 | test2
3 | test3
4 | test4
5 | test5
6 | test6
7 | test7
9 | test9
MySQL data insert (name of table usertest):
id | data | userid
----+---------+--------
1 | 1:4:6:9 | 2
2 | 1:2:3:4 | 5
3 | 1:2 | 7
Example outout :( print horizontal list name of table test where data = userid )
user id 2 choise : test1 - test4 - test6 - test9
Thanks

Answer 1

Assuming your usertest table has only the three columns listed in your example you should replace it with the following -
CREATE TABLE usertest (
data INTEGER NOT NULL,
userid INTEGER NOT NULL,
PRIMARY KEY (data, userid)
);
Then your data will look like -
+------+--------+
| data | userid |
+------+--------+
| 1 | 2 |
| 4 | 2 |
| 6 | 2 |
| 9 | 2 |
| 1 | 5 |
| 2 | 5 |
| 3 | 5 |
| 4 | 5 |
| 1 | 7 |
| 2 | 7 |
+------+--------+
Querying this data then becomes trivial -
SELECT usertest.userid, GROUP_CONCAT(test.name SEPARATOR ' - ')
FROM usertest
INNER JOIN test
ON usertest.data = test.id
GROUP BY usertest.userid
You can read more about GROUP_CONCAT here
You could use a PHP solution and store the possible checkbox values in an array indexed by their ids. Something like -
<?php
$db = new PDO('mysql:dbname=test;host=127.0.0.1', 'user', 'pass');
$sql = 'SELECT id, name FROM test';
$stmt = $db->prepare($sql);
$stmt->execute();
$array = array();
while ($row = $stmt->fetchObject()) {
$array[$row->id] = $row->name;
}
$sql = 'SELECT userid, data FROM usertest';
$stmt = $db->prepare($sql);
$stmt->execute();
while ($row = $stmt->fetchObject()) {
$data = explode(':', $row->data);
foreach($data as $key => $val) {
$data[$key] = $array[$val];
}
print "user id {$row->userid} choise : " . implode(' - ', $data) . "<br/>\n";
}