Question

Hi I have a postcode database which contains postcodes and the lat and lon details, In another table i have a list of companies with postcodes and want to add the lat and lon details to matching postcodes, rather than use a join query etc. Below is the code i am using, i have used something similar before, but i just can not work out why this isn’t working.

$host    = "localhost";
$username = "";
$password = "";
$database = "";
mysql_connect( $host, $username, $password );
mysql_select_db( $database ) or die( "Unable to select database" );


$query = "SELECT * FROM postcodes";      
$result = mysql_query($query) or die(mysql_error());
while($row = mysql_fetch_array($result)){   



$postcode = $row['postcode'];   
$lat = $row['lat']; 
$lon = $row['lon']; 



$result = mysql_query("UPDATE companies SET lat ='$lat' and lng ='$lon'  
WHERE postal_code = '$postcode'") 
or die(mysql_error());  

}

The error I am getting is: Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource in /home/visitrac/public_html/postcode.php on line 15

if i move the closed bracket so it is before the update then the error goes but no information gets into the database, which i assume is because it is out of the loop. I have tried all sorts of things but nothing seems to work and so any nudges in the right direction would be appreciated.

Thanks

Answer 1

There’s really no need for the loop through the postcode results. You can update all companies in a single SQL statement.

UPDATE companies c
    INNER JOIN postcodes p
        ON c.postal_code = p.postcode
    SET c.lat = p.lat,
        c.lng = p.lon