Question

I would like to trace the type of error that occurred while executing a query using PDO prepare and execute.

For example, if I had to insert email, Name, DOB, with the email requiring to be unique, instead of writing a special query to check if Email is already taken, I would like to trace the error that occurred and know the same.

Answer 1

You could use a try/catch block around the insert query and handle the double email in the exception handler.

$sql = "INSERT INTO `mystuff` (email, name ) VALUES (:email, :name)";

try {
  $sth = $dbh->prepare($sql);
  $sth->execute(array(':email' => $email, ':name' => $name)); 
}
catch (Exception $e)  {
  echo 'email already taken';
}

Of course you must configure PDO that it throws exceptions on errors.