mySQL Queries in Wordpress - php

Question

I have a mySQL database table called stock which holds a stock record on items for sale. When querying the database using PHP I have no issue, but when I try to do it through Wordpress it doesn't work.
my PHP is as follows
// Query the stock level
function QueryStock($cat) {
$query = "SELECT * FROM stock";
$result = mysql_query($query);
if (!$result) die ("Database access failed: " . mysql_error());
$rows = mysql_num_rows($result);
for ($j = 0 ; $j < $rows ; ++$j)
{
$row = mysql_fetch_row($result);
if ($row[0] == $cat) {
$catno=$row[0];
$supplier=$row[1];
$itemname=$row[2];
$category=$row[3];
$price=$row[4];
$stock=$row[5];
}
}
mysql_close($db_server);
echo "There are " . $stock . " bears";
}
$cat in the function attribute is the catalogue number of the item I am querying and the output is "There are 2 bears".
I put this in Wordpress and the webpage hangs. Then through Google searching, I found out about the $wpdb object being used by Wordpress at designmodo.com. So with some code condensing too, I changed it to...
function QueryStock($cat) {
$query = "SELECT * FROM stock WHERE catno = " . $cat;
global $wpdb;
$row = $wpdb->get_row($query, ARRAY_N);
$catno == $row[0];
$itemname = $row[2];
$price = $row[4];
$stock = $row[5];
echo "There are " . $stock . " bears";
}
Now the output is "There are bears" (missing the $stock value). I have been doing loads of Google searching to get where I am and I am having problems understanding it. Where am I going wrong?

Answer 1

Try:
function QueryStock($cat) {
$query = "SELECT * FROM stock WHERE catno = " . $cat;
global $wpdb;
$row = $wpdb->get_row($query);
$catno = $row->catno; //Column name in table
$itemname = $row->itemname; //Column name in table
$price = $row->price; //Column name in table
$stock = $row->stock; //Column name in table
echo "There are " . $stock . " bears";
}
Also, I would advise against using "SELECT *". Try to query only for the columns used. This is better for performance.
Edit: saw a typo. You had "$catno == $row..." in your code. You should only use one "="

Answer 2

Eureka!!!,
It's often something missed, and it was in the MySQL query.
The query should be SELECT * FROM stock WHERE catno = '$cat' making $query = "SELECT * FROM stock WHERE catno = '$cat'";
I have taken on board the "SELECT *" issue #eckes and #rickonline pointed out, went for separate queries and used $wpdb->get_var().
Working coding is..
function QueryStock($cat) {
$query1 = "SELECT catno FROM stock WHERE catno = '$cat'";
$query2 = "SELECT itemname FROM stock WHERE catno = '$cat'";
$query3 = "SELECT price FROM stock WHERE catno = '$cat'";
$query4 = "SELECT stock FROM stock WHERE catno = '$cat'";
global $wpdb;
$catno = $wpdb->get_var($query1);
$itemname = $wpdb->get_var($query2);
$price = $wpdb->get_var($query3);
$stock = $wpdb->get_var($query4);
echo "There are " . $stock . " bears";
}