PostgreSQL, Second Edition

Client 3—Processing Queries

libpqxx defines a small group of interrelated classes you use to execute commands and retrieve results. You already know about the connection class, which represents a connection to a server. In a libpqxx application, all commands are executed using an object derived from class transaction_base, which represents a server-side transaction. When you execute a command, the result set (that is, the data returned by the server) is stored in an object of class result—libpqxx creates a result object each time you execute a command. Inside a result object you'll find a collection of zero or more objects of class tuple. A tuple represents a single row in the result set and is a collection of one or more objects of type field ...