Question

I’ll try asking this again but without typing mistakes…. I’m connecting using MySQLi and using intentionally bad connection variables to trigger an error.

Working as expected:

  $conn = mysqli_connect("localhost","x","x","x");
  if (mysqli_connect_errno()) {
    echo "Couldn't establish database connection blah blah";
  }

This should work exactly the same, but it showing a “Can’t fetch MySQLi” warning:

  $conn = new mysqli("localhost","x","x","x");
  if ($conn->connect_errno) {
    echo "Couldn't establish database connection blah blah";
  }

Both methods are fine when the connection details are good, although that isn’t the point.

Answer 1

This didn’t work properly in some older versions of PHP.

If you are using a PHP version before 5.2.9, the $conn->connect_error (and I think also $conn->connect_errno) method did not function properly, and you had to use mysqli_connect_errno() instead.

The MySQLi constructor docs talk about this.

The mysqli->connect_error property only works properly as of PHP versions 5.2.9 and 5.3.0. Use the mysqli_connect_error() function if compatibility with earlier PHP versions is required.

// May need to use the procedural method, even in OO context...
$conn = new mysqli("localhost","x","x","x");
if (mysqli_connect_error()) {
    die('Connect Error (' . mysqli_connect_errno() . ') '
            . mysqli_connect_error());
}