4.6.1 The Maximum Value for a Column
4.6.2 The Row Holding the Maximum of a Certain Column
4.6.3 Maximum of Column per Group
4.6.4 The Rows Holding the Group-wise Maximum of a Certain Column
4.6.5 Using User-Defined Variables
4.6.8 Calculating Visits Per Day
以下是如何解决MySQL的一些常见问题的示例。
Some of the examples use the tableshopto hold the price of each article (item number) for certain traders (dealers). Supposing that each trader has a single fixed price per article, then (article,dealer) is a primary key for the records.
启动命令行工具mysql并选择一个数据库：
shell>mysql your-database-name
（在大多数MySQL安装中，可以使用名为test的数据库）。
您可以使用以下语句创建并填充示例表：
CREATE TABLE shop (
article INT(4) UNSIGNED ZEROFILL DEFAULT '0000' NOT NULL,
dealer CHAR(20) DEFAULT '' NOT NULL,
price DOUBLE(16,2) DEFAULT '0.00' NOT NULL,
PRIMARY KEY(article, dealer));
INSERT INTO shop VALUES
(1,'A',3.45),(1,'B',3.99),(2,'A',10.99),(3,'B',1.45),
(3,'C',1.69),(3,'D',1.25),(4,'D',19.95);
执行后，该表应具有以下内容：
SELECT * FROM shop;
+---------+--------+-------+
| article | dealer | price |
+---------+--------+-------+
| 0001 | A | 3.45 |
| 0001 | B | 3.99 |
| 0002 | A | 10.99 |
| 0003 | B | 1.45 |
| 0003 | C | 1.69 |
| 0003 | D | 1.25 |
| 0004 | D | 19.95 |
+---------+--------+-------+