Chapter 3 Tutorial Table of Contents 3.1 Connecting to and Disconnecting from the Server ...................................................................... 303 3.2 Entering Queries ....................................................................................................................... 304 3.3 Creating and Using a Database ................................................................................................ 307 3.3.1 Creating and Selecting a Database ................................................................................. 308 3.3.2 Creating a Table ............................................................................................................ 309 3.3.3 Loading Data into a Table .............................................................................................. 311 3.3.4 Retrieving Information from a Table ................................................................................ 312 3.4 Getting Information About Databases and Tables ....................................................................... 325 3.5 Using mysql in Batch Mode ...................................................................................................... 326 3.6 Examples of Common Queries .................................................................................................. 328 3.6.1 The Maximum Value for a Column ................................................................................. 328 3.6.2 The Row Holding the Maximum of a Certain Column ....................................................... 328 3.6.3 Maximum of Column per Group ...................................................................................... 329 3.6.4 The Rows Holding the Group-wise Maximum of a Certain Column .................................... 329 3.6.5 Using User-Defined Variables ......................................................................................... 330 3.6.6 Using Foreign Keys ....................................................................................................... 331 3.6.7 Searching on Two Keys ................................................................................................. 332 3.6.8 Calculating Visits Per Day .............................................................................................. 333 3.6.9 Using AUTO_INCREMENT ............................................................................................. 333 3.7 Using MySQL with Apache ....................................................................................................... 336 This chapter provides a tutorial introduction to MySQL by showing how to use the  mysql  client program to create and use a simple database.  mysql  (sometimes referred to as the “terminal monitor”  or just “monitor” ) is an interactive program that enables you to connect to a MySQL server, run queries, and view the results.  mysql  may also be used in batch mode: you place your queries in a file beforehand, then tell mysql  to execute the contents of the file. Both ways of using  mysql  are covered here. To see a list of options provided by  mysql , invoke it with the  --help  option: shell>  mysql --help This chapter assumes that  mysql  is installed on your machine and that a MySQL server is available to which you can connect. If this is not true, contact your MySQL administrator. (If  you  are the administrator, you need to consult the relevant portions of this manual, such as Chapter 5,  MySQL Server Administration .) This chapter describes the entire process of setting up and using a database. If you are interested only in accessing an existing database, you may want to skip the sections that describe how to create the database and the tables it contains. Because this chapter is tutorial in nature, many details are necessarily omitted. Consult the relevant sections of the manual for more information on the topics covered here. To connect to the server, you usually need to provide a MySQL user name when you invoke  mysql  and, most likely, a password. If the server runs on a machine other than the one where you log in, you must also specify a host name. Contact your administrator to find out what connection parameters you should use to 3.1 Connecting to and Disconnecting from the Server 303