This class implements a wrapper to access PostgreSQL databases. It can: - Establish database connections - Execute SQL queries - Fetch the name, size and type of query result columns - Fetch whole result sets into arrays - Display information about errors, query results and for debugging - Get the number result set rows or affected rows by a query - Get the last inserted identifier of row with a key generated from a sequence - Execute a query and return the results in a single call - Escape text field values - Insert or update rows using data from arrays