Mysql search with semi colon delimited string - php

Question

I have 2 tables that look like this
table A table B
id | data id | features
--------- --------------
1 | blue 1A | 1;2
2 | red 2B | 1;2;3
3 | yellow 3B | 3;1
...... ......
What i plan to do is something like this, where i query one table. loop thru the array of results and explode the data with the semicolon delimiter. then loop thru that new array and query it to get the data (note code below not tested)
$sql = "SELECT * FROM `tableB` WHERE `id`= '2B' LIMIT 1";
$query = $db->query($sql);
while ($row = mysql_fetch_array($query)) {
$arr = explode(';', $row['features']);
for ($i = 0; $i < sizeof($arr); $i++)
{
$sql2 = "SELECT * FROM `tableA` WHERE `id`="'.$arr[$i].'"";
$query2 = $db->query($sql2);
while ($row2 = mysql_fetch_array($query2)) {
$r[] = $row2['data'];
}
}
}
print_r($r);
is there a way i can achieve this just in mysql, where i match the column in tableB with the ID's in tableA? or maybe by not using a nested loop? performance is key. coz both tables have more than 25k rows of data.
thanks in advance

Answer 1

Check out this code. Reduced few loops.
$sql = "SELECT * FROM `tableB` WHERE `id`= '2B' LIMIT 1";
$query = $db->query($sql);
$arr = explode(';', $row['features']);
$str = implode(",", $arr);
$sql2 = "SELECT * FROM `tableA WHERE id IN ({$str});";
$query2 = $db->query($sql2);
while ($row2 = mysql_fetch_array($query2)) {
$r[] = $row2['data'];
}

Answer 2

What you are looking for is the IN function
This will take an array of id's and give you every result in a single query.
So your code should look like this after you apply it
while ($row = mysql_fetch_array($query)) {
$new_query = str_replace(";", ",", $row['features']);
$sql2 = "SELECT * FROM `tableA` WHERE `id` IN ($new_query)";
$query2 = $db->query($sql2);
while ($row2 = mysql_fetch_array($query2)) {
$r[] = $row2['data'];
}
}