Now that we’ve created a database object, $db, we can call its methods to fetch data from the database.

Let’s take a look at an example database. It contains a books table with a list of books with their id, title, author, and published year.

We’ll begin with a query to fetch book titles. We’ll use the query() method on the $db object to create and execute the query. We can do this by referencing the $db object with the object operator (->) before calling the query() method.

// Create the query
$bookQuery = $db->query('SELECT title FROM books');

Does the syntax in parenthesis look familiar? That’s because it’s a regular SQL query that is understood by the database.

Now let’s fetch the result of the query and assign it to the $book variable. We do this by calling the fetch() method on $bookQuery.

// Fetch the first book and assign it to $book 
$book = $bookQuery->fetch(); 

Although our SELECT statement above queries the database for all book titles, the fetch() method returns only one result.

To return a list of all book titles, we can use the fetchAll() method instead:

// Fetch all books and assign them to $books
$books = $bookQuery->fetchAll(); 

If we use print_r to look at the value of $book, we’ll see that the data is returned as both an ordered (indexed) and associative array.

Array ( [title] => Don Quixote [0] => Don Quixote )

We can change that by setting a fetch mode, which tells PDO in what format to return our data. To get our book as an associative array, we pass PDO::FETCH_ASSOC as an argument to the fetch() method.

// Fetch the next row and assign the result to $book
$book = $bookQuery->fetch(PDO::FETCH_ASSOC);

If we check $book now, we’ll see:

Array ( [title] => Don Quixote )