Question

I want to use max clause to find the maximum value according to field name
Till now i had used this

SELECT MAX(sl) FROM associate where br_code=$_REQUEST[br_code]

but this isn’t worked

Friend as from my question it is clear that i want to find the max value of the sl from a group of br_code name which should be selected from the where clause.

Answer 1

This selects your data, while being secure from SQL Injection attacks.

$query = "SELECT mx FROM (SELECT MAX(s1) AS mx, br_code FROM associate GROUP BY br_code) AS T1 WHERE T1.br_code=" . mysql_real_escape_string($_REQUEST['br_code']);

Please note that when using mysql_real_escape_string you have to already have an established connection. See this for more information.