Optimizing PHP script - php

Question

I have a working script that selects image fields in all tables and empty their values if the physical file doesnt exist.
$query1 = "SELECT table_name,column_name
FROM information_schema.columns
WHERE table_schema='schemaname' AND column_name like '%image%' or column_name='video'";
$result1 = mysql_query($query1) or die(mysql_error() . " -- " . $query1);
while($row1 = mysql_fetch_row($result1)){
if (!strpos($row1[0],'backup') > 0){
$sql = "Select COLUMN_NAME FROM information_schema.columns WHERE TABLE_NAME = '".$row1[0]."' AND EXTRA = 'auto_increment'";
$resultcol = mysql_query($sql);
$rowcol = mysql_fetch_row($resultcol);
$query2 = "SELECT " . $row1[1] . ", " .$rowcol[0] . "
FROM " . $row1[0] . "
WHERE " . $row1[1] . " != '' AND " . $row1[1] . " IS NOT NULL
";
echo $query2 . "<br>";
$result2 = mysql_query($query2) or die(mysql_error() . " -- " . $query2);
while ($rowdb = mysql_fetch_row($result2)){
if (!strpos($rowdb[0],'facebook') > 0 && !file_exists($img_root.'/'.$rowdb[0])){
$sql = "UPDATE ".$row1[0]." SET ". $row1[1] . " = '' WHERE " . $rowcol[0]. "= ".$rowdb[1];
echo $sql . "<br><br>";
$delete_count++;
//mysql_query("UPDATE ".$row1[0]." SET ". $row1[1] . " = '' WHERE id = ".$row1["id"]);
}
}
}
}
The script is working fine, but it takes time though, I was wondering if there is a smarter way (more optimized) to get the same function ? Thanks

Answer 1

You have several options.
The first, and IMHO the best option - is to use an ORM -
I recommend Idiorm, Doctrine, or Propel.
Then, you would use something like (in idiorm) fetch_all and loop through that, instead of through the mysql_fetch_row()
Second, you should switch to mysqli -- the functions you are using are deprecated in PHP5.5
Third -- you could just use either mysql_fetch_array or mysql_fetch_all (I'm not sure, but I would be on the latter)
The key thing here is:
Do not loop mysql functions.

Answer 2

Performance wise the problem is that you are looping through a result set, and performing queries for each row.
However with your output it is difficult to eliminate this. Otherwise you might be able to do the whole script in a single SQL statement.
Minimal clean up to just remove one of the selects:-
<?php
$query1 = "SELECT a.table_name, a.column_name, b.COLUMN_NAME AS auto_inc_col
FROM information_schema.columns a
INNER JOIN information_schema.columns b
ON a.table_name = b.table_name AND b.EXTRA = 'auto_increment'
WHERE table_schema='schemaname' AND column_name like '%image%' or column_name='video'";
$result1 = mysql_query($query1) or die(mysql_error() . " -- " . $query1);
while($row1 = mysql_fetch_assoc($result1))
{
if (!strpos($row1['table_name'],'backup') > 0)
{
$query2 = "SELECT " . $row1['column_name'] . ", " .$row1['auto_inc_col'] . "
FROM " . $row1['table_name'] . "
WHERE " . $row1['column_name'] . " != '' AND " . $row1['column_name'] . " IS NOT NULL
";
echo $query2 . "<br>";
$result2 = mysql_query($query2) or die(mysql_error() . " -- " . $query2);
while ($rowdb = mysql_fetch_row($result2))
{
if (!strpos($rowdb[0],'facebook') > 0 && !file_exists($img_root.'/'.$rowdb[0]))
{
$sql = "UPDATE ".$row1['table_name']." SET ". $row1['column_name'] . " = '' WHERE " . $row1['auto_inc_col']. "= ".$rowdb[1];
echo $sql . "<br><br>";
$delete_count++;
//mysql_query("UPDATE ".$row1['table_name']." SET ". $row1['column_name'] . " = '' WHERE id = ".$row1["id"]);
}
}
}
}
?>