SQL SELECT Query use for search - php

Question

I have three variables:
$school
$class
$subject
And a search String $searchquery
I want to search my database for the rows that match the Search Query... Currently I am using this:
$searchquery = str_replace(" ","|",$searchquery);
$sql = "
SELECT * FROM filedetails
WHERE school RLIKE '$searchquery'
OR class RLIKE '$searchquery'
OR subject RLIKE '$searchquery'";
Now, how this works, Suppose I enter Mathematics Class X. It converts the string into Mathematics|Class|X which is fine and search the Database and prints the results...
But there is one error:
It is printing all the rows which have either Mathematics or Class or X in them, so my output includes all the Classes of all Schools of Mathematics and All Subjects of All Schools of Class X...
Whereas I want it to show me All Schools having Mathematics and Class X...
P.S. - I have tried using AND instead of OR, but now I get empty result because no School Matches my Query String...

Answer 1

One way of doing is first make different 2-D Arrays of all the data searches and then take their intersection, so this will give the common row which matches all the keywords...
$sql = "SELECT * FROM filedetails";
$query = mysql_query($sql);
$array1 = array();
while ($row = mysql_fetch_array($query))
{
$array1[] = $row;
}
$sql = "SELECT * FROM filedetails WHERE school RLIKE '$searchquery'";
$query = mysql_query($sql);
$array2 = array();
while ($row = mysql_fetch_array($query))
{
$array2[] = $row;
}
$sql = "SELECT * FROM filedetails WHERE subject RLIKE '$searchquery'";
$query = mysql_query($sql);
$array3 = array();
while ($row = mysql_fetch_array($query))
{
$array3[] = $row;
}
$sql = "SELECT * FROM filedetails WHERE class RLIKE '$searchquery'";
$query = mysql_query($sql);
$array4 = array();
while ($row = mysql_fetch_array($query))
{
$array4[] = $row;
}
Now, what this code is doing that it is searching individually for every field and making separate result for each Query of each field, now We will be taking Intersection of the arrays so as to get the common row having the keywords
But there is one problem, suppose the $searchquery contains Details about School and Class, but no information about Subject, then the $array3 will be null, as the query will result NULL, then we need to consider handling null arrays which have been solved in Another Question Here...
Hope this helps... :)