MYSQL 使用序列号
使用AUTO_INCERMENT 来定义mysql> CREATE TABLE insect
-> (
-> id INT UNSIGNED NOT NULL AUTO_INCREMENT,
-> PRIMARY KEY (id),
-> name VARCHAR(30) NOT NULL, # type of insect
-> date DATE NOT NULL, # date collected
-> origin VARCHAR(30) NOT NULL # where collected
);
Query OK, 0 rows affected (0.02 sec)
mysql> INSERT INTO insect (id,name,date,origin) VALUES
-> (NULL,'housefly','2001-09-10','kitchen'),
-> (NULL,'millipede','2001-09-10','driveway'),
-> (NULL,'grasshopper','2001-09-10','front yard');
Query OK, 3 rows affected (0.02 sec)
Records: 3Duplicates: 0Warnings: 0
mysql> SELECT * FROM insect ORDER BY id;
+----+-------------+------------+------------+
| id | name | date | origin |
+----+-------------+------------+------------+
|1 | housefly | 2001-09-10 | kitchen |
|2 | millipede | 2001-09-10 | driveway |
|3 | grasshopper | 2001-09-10 | front yard |
+----+-------------+------------+------------+
3 rows in set (0.00 sec)上述代码解析： 以上实例中 创建了数据表 inset ，inset 中的 id 无需指定值可实现自动增长。
获取auto_increment 的值： 使用函数 LAST-INSERT_ID() 函数来获取最后的插入表中的自增列的值。、
帖段PHP代码：
mysql_query ("INSERT INTO insect (name,date,origin)
VALUES('moth','2001-09-14','windowsill')", $conn_id);
$seq = mysql_insert_id ($conn_id);
重置序列： 对剩下 的数据重新排序
mysql> ALTER TABLE insect DROP id;
mysql> ALTER TABLE insect
-> ADD id INT UNSIGNED NOT NULL AUTO_INCREMENT FIRST,
-> ADD PRIMARY KEY (id);
设置序列的开始值：
ysql> CREATE TABLE insect
-> (
-> id INT UNSIGNED NOT NULL AUTO_INCREMENT,
-> PRIMARY KEY (id),
-> name VARCHAR(30) NOT NULL,
-> date DATE NOT NULL,
-> origin VARCHAR(30) NOT NULL
)engine=innodb auto_increment=100 charset=utf8;
或者可以在表创建成功后，通过以下语句来实现
ALTER TABLE t AUTO_INCREMENT = 100;
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