Great job on completing this lesson. Let’s take a moment to review some of the material covered in this lesson:

• Databases store data for PHP applications.
• PDO lets us write code that will work with many common database systems.
• We write queries by inserting SQL into the query() method.
• SQL queries with user-defined parameters (variables) are vulnerable to SQL injection.
• We use prepared statements to prevent SQL injection.
• Prepared statements use the prepare() and execute() methods and send SQL commands and data separately.
• For exception handling, we wrap code in a try/catch block.
• We use exception handling to catch and handle exceptions when our program throws them.
• We can use methods on the exception object to troubleshoot exceptions.

You’re now well on your way to creating database-driven PHP applications!