I am switching from plain mysql in php to PDO and I have noticed that the common way to test for errors is using a try / catch combination instead of if / else combinations.
In general, try-catch blocks are great because they will break (move to the catch statement) whenever the exception occurs. If-else blocks rely on you predicting when the error will happen.
Edit:
Also, catch blocks won't stop your code from halting when an error is hit.