Generating a sql query in php using for loop

Question

CODE :

 $nerd_result = mysql_query("select * from nerd_profile where nerd_reg_no = '$reg_no'");
$nerd_data = mysql_fetch_array($nerd_result);
$tags = array();
$tags = explode(",",$nerd_data['nerd_interests']);
for($i = 0; $i < sizeof($tags)-1; $i++)
{
    if($i != sizeof($tags)-2)
    {
    $sub_query = $sub_query."`tags` like %".$tags[$i]."% or "; 
    }
    else 
    {
        $sub_query = $sub_query."`tags` like %".$tags[$i]."% ";
    }
}



 $proper_query = "select * from `qas_posts` where ".$sub_query." and `post_date` like '%$today%'";
 $result = mysql_query($proper_query);
 while($each_qas = mysql_fetch_array($result))

Description :

I am adding the like clause along with php variable in a string and concatenating it with the further variables with like clause to come. In the end when I echo I get the perfect query that I want but

mysql_fetch_array()

does not accept that generated query rather if I hard code it , it works perfect what am I doing wrong ?? can I do that ??

This %".$tags[$i]."% needs to be this '%".$tags[$i]."%'. You're missing quotes. Also, it's typically a good idea to initialize your variables, e.g. $sub_query = "";. — imtheman
– imtheman, Commented Sep 10, 2014 at 21:36
ohh my goodness .... the quotes... why didn't I see that ... I have been looking on the internet for an hour now .. Thanks :) — Uzumaki Naruto
– Uzumaki Naruto, Commented Sep 10, 2014 at 21:38
PSA: The mysql_* functions are deprecated in PHP 5.5. It is not recommended for writing new code as it will prevent you from upgrading in the future. Instead, use either MySQLi or PDO and be a better PHP Developer. — Jason McCreary
– Jason McCreary, Commented Sep 10, 2014 at 21:40

imtheman · Accepted Answer · 2014-09-10 21:43:21Z

2

When doing string comparisons in mysql you need to make sure you have quotes around your comparison value.

$sub_query = $sub_query."`tags` like '%".$tags[$i]."%' or ";

and

$sub_query = $sub_query."`tags` like '%".$tags[$i]."%' ";

answered Sep 10, 2014 at 21:43

imtheman

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