Use pgsql to connect to your postgreSQL database. Add and to the php.ini file.

Basic example

This simple example shows how to connect, execute a query, print a result row and disconnect from a PostgreSQL database.

 $host = "hostname";
 $user = "username";
 $pass = "password";
 $db = "database";

 // Open a PostgreSQL connection
 $con = pg_connect("host=$host dbname=$db user=$user password=$pass")
   or die ("Could not connect to server\n");
 $query = 'SELECT * FROM table';
 $results = pg_query($con, $query) or die('Query failed: ' . pg_last_error());
 $row = pg_fetch_row($results);
 echo $row[0] . "\n";
 // Closing connection