I have a database set up which assigns a school, and its pertinent information, to a specific id for "calling" purposes. However, I am having a little trouble getting this stuff to come together. The error message that I receive when I click the "go" button is that there is an "Unknown column '$id' in 'where clause' " There definitely is the id column in the database, so I thought defining the variable was the problem, but looking around on some sites, my code seems to be ok. This is very frustrating, and I was wondering if someone could possibly chime in with any help that they could. Thanks in advance. My code is below:

<form id="form" method="get" action="schoolphp.php">
<select name="id" >
<option value="1">School #1</option>
<option value="2">School #2</option>
<input type="submit" value="Go" />

PHP Code:

<?php
//Connect To Database
$hostname='x.x.com';
$username='uname';
$password='pass';
$dbname='dbname';
$usertable=school;


mysql_connect($hostname,$username, $password) OR DIE ('Unable to connect to database! Please try again later.');
mysql_select_db($dbname);
// Retrieve all the data from the "school" table

$id=$_GET['id'];

$result = mysql_query('SELECT * FROM school WHERE id=$id')
or die(mysql_error());  

// store the record of the "school" table into $row
$row = mysql_fetch_array( $result );
// Print out the contents of the entry 

echo "Name: ".$row['school'];
echo " GPA: ".$row['gpa'];

?>

Try this:

PHP Code:

 <?php
//Connect To Database
$hostname='x.x.com';
$username='uname';
$password='pass';
$dbname='dbname';
$usertable=school;


mysql_connect($hostname,$username, $password) OR DIE ('Unable to connect to database! Please try again later.');
mysql_select_db($dbname);
// Retrieve all the data from the "school" table

$id=$_GET['id'];

    $query = "SELECT * FROM school WHERE id={$id}";
    // execute query
    $result = mysql_query($query) or die ("Error in query: $query. ".mysql_error());

// store the record of the "school" table into $row
$row = mysql_fetch_array( $result );
// Print out the contents of the entry 

echo "Name: ".$row['school'];
echo " GPA: ".$row['gpa'];

?>

Two main changes: the important one: the Inline Variable. When you use a PHP defined Variable in a string, you have to put {} around it. The second change being, just pulling the query into its own Variable.

You don't need to use {} in php

PHP Code:

$query = "SELECT * FROM school WHERE id={$id}"; 


you can escape the string and use . to join the string and variable $id

PHP Code:

$query = "SELECT * FROM school WHERE id=".$id; 


Actually, you can just do this

PHP Code:

$query = "SELECT * FROM school WHERE id=$id"; 


As long as your using the double quotes ("). If you use single quotes (') the $id variable will not be replaces by it's value, it will simply print $id as in the error message above.

<_< All 3 should work fine. I just like the {$ver} method, because my editor (PSPad) will color code them... making them easier to find .

Originally Posted by lizciz

Actually, you can just do this

PHP Code:

$query = "SELECT * FROM school WHERE id=$id"; 


As long as your using the double quotes ("). If you use single quotes (') the $id variable will not be replaces by it's value, it will simply print $id as in the error message above.

but for varchar u would need single quotes