When we discussed the connection strings (or the data source names for PDO), we saw that the connection string starts with the driver name followed by a semicolon. PDO also supports configuration files—a file that contains the connection string. For example, we can create a file called pdo.dsn in the directory where we can keep the application files and put the connection string there:
mysql:host=localhost;dbname=pdo or sqlite:/www/hosts/localhost/pdo.db
Alternatively, we can create two files, mysql.dsn and sqlite.dsn, containing the first and the second connection strings respectively.
Then in the PDO constructor, we can specify the configuration file path or URL, not just the connection string:
uri:./pdo.dsn
PDO will read the file and use the connection string specified there. The advantage of using this method is that you can specify not just a local file, but any URL so that a remote file can be included (provided...