MySQL Cookbook

Using AUTO_INCREMENT To Set Up a Sequence Column

Problem

You want to include a sequence column in a table.

Solution

Use an AUTO_INCREMENT column.

Discussion

This section provides the basic background on how AUTO_INCREMENT columns work, beginning with a short example that demonstrates the sequence-generation mechanism. The illustration centers around a bug-collection scenario: your son (eight-year-old Junior) is assigned the task of collecting insects for a class project at school. For each insect, Junior is to record its name (“ant,” “bee,” and so forth), and its date and location of collection. You have long expounded the benefits of MySQL for record-keeping to Junior since his early days, so upon your arrival home from work that day, he immediately announces the necessity of completing this project and then, looking you straight in the eye, declares that it’s clearly a task for which MySQL is well-suited. Who are you to argue? So the two of you get to work. Junior already collected some specimens after school while waiting for you to come home and has recorded the following information in his notebook:

Name	Date	Origin
millipede	2001-09-10	driveway
housefly	2001-09-10	kitchen
grasshopper	2001-09-10	front yard
stink bug	2001-09-10	front yard
cabbage butterfly	2001-09-10	garden
ant	2001-09-10	back yard
ant	2001-09-10	back yard
millbug	2001-09-10	under rock

Looking over Junior’s notes, you’re pleased to see that even at his tender age he has learned to write ...