As we have seen in the previous section, the PDOStatement class allows us to retrieve some information about the data contained in the result set. This information is called metadata, and you probably have already used some of it one way or another.
The most important metadata about a result set is, of course, the number of rows it contains. We can use the row count to enhance user experience by, for example, paginating long result sets. Our example library application is still quite small, with only three books so far, but as our database grows, we surely will need some tools to get the total row count for every table displayed and paginate it for easy browsing.
Traditionally, you would use the mysql_num_rows(), sqlite_num_rows() function or the pg_num_rows() function (depending on your database) to get the total number of rows returned by the query. In PDO, the method responsible for retrieving the number of rows is called PDOStatement::rowCount(). However...