Storing a string in a variable in php and searching for that variable in mysql database?

Question

If I search for a string directly it works properly but whenever I store that string in a variable and try to search that it gives me:

bool(false)

here is my code

<?php
 $mysqli = new mysqli("localhost", "root", "password", "database");
 $roll_no='9999-SO-12';
 echo $roll_no;
 $res = $mysqli->query("SELECT name,title FROM student_data WHERE roll_no=$roll_no");

 var_dump($res);
  ?>

But whenever I do it directly It works fine for example like this

<?php
 $mysqli = new mysqli("localhost", "root", "password", "database");
 $roll_no='9999-SO-12';
 $res = $mysqli->query("SELECT name,title FROM student_data WHERE roll_no='9999-SO-12'");

 var_dump($res);
  ?>

So what am I doing wrong? What's the solution?

@saty I tried your code but it was partially solving my problem. so using ' ".$roll_no." ' instead of '$roll_no' proved helpful. Further when I tried to store the variable using $_POST your solution wasn't getting the required info but the other one was.So that's why I went for that. BTW thank you for answering. — Naqvi
– Naqvi, Commented Apr 11, 2015 at 9:17

Jimmy T. · Accepted Answer · 2015-04-11 08:46:30Z

1

You are passing the parameter as integer though it is string. Change your query to:

$mysqli->query("SELECT name,title FROM student_data WHERE roll_no='".$roll_no."'");

edited Apr 11, 2015 at 8:46

Jimmy T.

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answered Apr 11, 2015 at 8:30

Danyal Sandeelo

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Jimmy T. · Accepted Answer · 2015-04-11 08:41:03Z

1

Do some changes like this:

$res = $mysqli->query("SELECT name,title FROM student_data WHERE roll_no='".$roll_no."'");

edited Apr 11, 2015 at 8:41

Jimmy T.

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answered Apr 11, 2015 at 8:32

Pranay Aher

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Comments

kguest · Accepted Answer · 2015-04-11 13:01:38Z

1

Please try this.

 $res = $mysqli->query("SELECT name,title FROM student_data WHERE roll_no='".$roll_no."'");

edited Apr 11, 2015 at 13:01

kguest

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answered Apr 11, 2015 at 11:54

Krishna Chandegara

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