Need HELP in converting MySQL to MySQLI in my PHP script?

Question

I need some help in converting my script from using mysql to mysqli I have been trying for ever to do this and keep getting errors I have read articles on how to do this and still can get it to work.

Here is the original working script below.

<?php

require_once ('./mysqli_connect.php'); // Connect to the db.

if (isset($_POST['submitted'])) {

if ($dbc = mysql_connect (DB_HOST, DB_USER, DB_PASSWORD)) { // Make the connnection.

 if (!mysql_select_db (DB_NAME)) { // If it can't select the database.

  // Handle the error.
  trigger_error("Could not select the database!\n<br />MySQL Error: " . mysql_error());
  exit();

 } // End of mysql_select_db IF.

} else { // If it couldn't connect to MySQL.

 // Print a message to the user, include the footer, and kill the script.
 trigger_error("Could not connect to MySQL!\n<br />MySQL Error: " . mysql_error());
 exit();

} // End of $dbc IF.

// grab the tag
$tag = mysql_real_escape_string($_POST['tag']);

// see if the tag already exists and potentially what the current count is
$query = "SELECT id, count, page FROM tags WHERE tag='$tag'";
$result = mysql_query($query);

//--if there is a row, that means the tag exists
if(mysql_num_rows($result))
{
//--pull out the tag ID and the current count and increment by one.
  $tag_info = mysql_fetch_array($result);
  $tag_info_id = $tag_info["id"];
  $tag_info_count = $tag_info["count"] + 1;

//--update the table with the new count
  $sql_update_cnt = "UPDATE tags SET count='$tag_info_count' 
       WHERE id='$tag_info_id'";
  mysql_query($sql_update_cnt);

  echo "$tag now with $tag_info_count instances";
}
else
{
// tag is not there, so insert a new instance
  $query = "INSERT INTO tags (tag, count) VALUES ('$tag', 1)";
if (!mysql_query($query, $dbc))
  {
  die('Error: ' . mysql_error());
  }
echo "1 record added";
}
mysql_close($dbc);
}
?>

Here is the errors I keep getting.

Warning: mysqli_select_db() expects exactly 2 parameters, 1 given on line 13

Warning: mysqli_error() expects exactly 1 parameter, 0 given on line 16

Answer 1

It's all a matter of changing mysql to mysqli.

For example, you could call mysqli_query just like you do mysql_query here.

When you call these functions, you need to pass in the database reference as the first parameter.

See the mysqli function reference here

Answer 2

It's been a while since I've done a mysql->mysqli conversion (like 2 or 3 years), but IIRC there are some functions for which you also have to reverse the parameter order. Isn't that lovely?

Answer 3

If you're going to go through the hassle, I would really recommend you consider PDO instead.