creating unique page title slugs php

Question

I have a function for creating unique slug for a page title. It checks if the slug is available in the pages table then creates a unique slug by adding a '-int' accordingly. The function works fine for the first three entries eg for 'test slug' entered three time will create 'test-slug-1', 'test-slug-2' and 'test-slug-3'. Then after that I get an error "Fatal error: Maximum execution time of 30 seconds exceeded" for the fourth entry. There should be some problem with the logic, can anyone help me find it please.Below is the code:

function createSlug($title, $table_name, $field_name) {

global $db_connect;

$slug = preg_replace("/-$/","",preg_replace('/[^a-z0-9]+/i', "-", strtolower($title)));

$counter = 1;

do{

  $query = "SELECT * FROM $table_name WHERE  $field_name  = '".$slug."'";
  $result = mysqli_query($db_connect, $query) or die(mysqli_error($db_connect));


  if(mysqli_num_rows($result) > 0){
      $count = strrchr($slug , "-"); 
      $count = str_replace("-", "", $count);
      if($count > 0){

          $length = count($count) + 1;
          $newSlug = str_replace(strrchr($slug , "-"), '',$slug);
          $slug = $newSlug.'-'.$length;

          $count++;

      }else{
          $slug = $slug.'-'.$counter;
      }  

  }

  $counter++; 
  $row = mysqli_fetch_assoc($result);

}while(mysqli_num_rows($result) > 0);

return $slug;

}

Answer 1

Just hit the database once, grab everything at once, chances are that's the biggest bottleneck.

$query = "SELECT * FROM $table_name WHERE  $field_name  LIKE '".$slug."%'";

Then put your results in an array (let's say $slugs)

//we only bother doing this if there is a conflicting slug already
if(mysqli_num_rows($result) !== 0 && in_array($slug, $slugs)){
    $max = 0;

    //keep incrementing $max until a space is found
    while(in_array( ($slug . '-' . ++$max ), $slugs) );

    //update $slug with the appendage
    $slug .= '-' . $max;
}

We use the in_array() checks as if the slug was my-slug the LIKE would also return rows such as

my-slug-is-awesome
my-slug-is-awesome-1
my-slug-rules

etc which would cause issues, the in_array() checks ensure that we are only checking against the exact slug that was entered.

Why don't we just count the results and +1?

This is because if you had multiple results, and deleted a few, your next slug could well conflict.

E.g.

my-slug
my-slug-2
my-slug-3
my-slug-4
my-slug-5

Delete -3 and -5 leaves us with

my-slug
my-slug-2
my-slug-4

So, that gives us 3 results, the next insert would be my-slug-4 which already exists.

Why don't we just use ORDER BY and LIMIT 1?

We can't just do an order by in the query because ^{the lack of} natural sorting would make my-slug-10 rank lower than my-slug-4 as it compares character by character and 4 is higher than 1

E.g.

m = m
y = y
- = -
s = s
l = l
u = u
g = g
- = -
4 > 1 !!!
  < 0 (But the previous number was higher, so from here onwards is not compared)