PHP multiple dropdown boxes with separated tables - php

Question

okay as the title says I have a lot of tables and I need to display them in different drop down boxes. I have so far got the first table to display inside of a drop down box but I'm not really sure how too get the next table display.
<?php
$link = mysql_connect('server', 'user', 'password');
if (!$link) {
die('Could not connect: ' . mysql_error());
}
echo 'Connected successfully';
$selected = mysql_select_db("database",$link)
or die("Could not select examples");
$sql="SELECT * FROM MOBO CPU, RAM,GPU, PSU, COMPUTERCASE";
$result = mysql_query($sql);
echo "<select name='mobo'>";
while ($row = mysql_fetch_array($result)) {
echo '<option value="'.$row["id"].'">'.$row["mobo"].'</option>';
}
echo "</select>";
?>
so this is my php so far and this is how the database looks.
CREATE TABLE MOBO (id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,mobo VARCHAR(50) UNIQUE,quantity INT,price DECIMAL(18,2));
CREATE TABLE CPU (id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, cpu VARCHAR(50) UNIQUE, quantity INT, price DECIMAL(18,2));
CREATE TABLE RAM (id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,ram VARCHAR(50) UNIQUE,quantity INT,price DECIMAL(18,2));
and so on also I was hoping for somebody if they manager to fix my problem to explain in detail of how its done I'm a PHP Newb.

Answer 1

First of all, you're using mysql_* functions and they are removed in the latest version of PHP. While it works now, you will have an issue upgrading to a later version of PHP in the future. Use Mysqli or PDO (PDO is my preference)
Secondly, use lower case in identifiers such as your table names. This code might work on Windows, but if you ever migrate to Linux all of this will be case sensitive and this code will fail to work.
And what I do not understand in this code, while ($row = mysql_fetch_array($result)) {. mysql_fetch_array() returns the complete set of the result from the database. A while loop will constantly redefine it's value and you should instead use foreach($var = mysql_fetch_array(...) as $key => $value){} and then still it would be better to define $var in my example separately before using it in a foreach loop.
Then I think your issues are resolved.
$sql="SELECT * FROM mobo, cpu, ram, gpu, psu, case";
if($result = mysql_query($sql) != false){ // you should actually check if the query ran successfully.
$data = mysql_fetch_array($result);
//echo "<select name='mobo'>";
foreach($data as $row => $value){
echo $row, $value, "</br>";
}
//echo "</select>";
}
And last of all, selecting everything from multiple tables is a bad database setup. It will drag you down once you have a lot of results in the database and then it will be an issue to resolve this. Its perhaps better to use inner or outer joins by id.