MySQL 序列 AUTO_INCREMENT详解及实例代码

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: 3 Duplicates: 0 Warnings: 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)

$dbh->do ("INSERT INTO insect (name,date,origin)
VALUES('moth','2001-09-14','windowsill')");
my $seq = $dbh->{mysql_insertid};

mysql_query ("INSERT INTO insect (name,date,origin)
VALUES('moth','2001-09-14','windowsill')", $conn_id);
$seq = mysql_insert_id ($conn_id);

mysql> ALTER TABLE insect DROP id;
mysql> ALTER TABLE insect
  -> ADD id INT UNSIGNED NOT NULL AUTO_INCREMENT FIRST,
  -> ADD PRIMARY KEY (id);

mysql> CREATE TABLE insect
  -> (
  -> id INT UNSIGNED NOT NULL AUTO_INCREMENT = 100,
  -> PRIMARY KEY (id),
  -> name VARCHAR(30) NOT NULL, # type of insect
  -> date DATE NOT NULL, # date collected
  -> origin VARCHAR(30) NOT NULL # where collected
);

mysql> ALTER TABLE t AUTO_INCREMENT = 100;