MySQL Cookbook, 2nd Edition

Connecting, Selecting a Database, and Disconnecting

Problem

You need to establish a connection to the server to access a database, and to shut down the connection when you’re done.

Solution

Each API provides routines for connecting and disconnecting. The connection routines require that you provide parameters specifying the hostname that is running the MySQL server and the MySQL account that you want to use. You can also select a default database.

Discussion

The programs in this section show how to perform three fundamental operations that are common to the vast majority of MySQL programs:

Establishing a connection to the MySQL server

Every program that uses MySQL does this, no matter which API you use. The details on specifying connection parameters vary between APIs, and some APIs provide more flexibility than others. However, there are many common elements. For example, you must specify the host that is running the server, as well as the username and password for the MySQL account to use for accessing the server.

Selecting a database

Most MySQL programs select a default database.

Disconnecting from the server

Each API provides a way to close an open connection. It’s best to close the connection as soon as you’re done using the server so that it can free up any resources that are allocated to servicing the connection. Otherwise, if your program performs additional computations after accessing the server, the connection will be held open longer than necessary. It’s also preferable to close ...