mysql序列号生成器 mysql自定义函数生成序列号的例子

CREATE TABLE `seq` ( 
  `name` varchar(20) NOT NULL, 
  `val` int(10) unsigned NOT NULL, 
  PRIMARY KEY (`name`) 
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

INSERT INTO seq VALUES('one',100); 
INSERT INTO seq VALUES('two',1000); 

CREATE FUNCTION seq(seq_name char (20)) returns int 
begin 
 UPDATE seq SET val=last_insert_id(val+1) WHERE name=seq_name; 
 RETURN last_insert_id(); 
end 

mysql> SELECT seq( 'one' ) ,seq( 'two' ) ,seq( 'one' ) ,seq( 'one' ) ;
+------------+------------+------------+------------+
| seq( 'one' ) | seq( 'two' ) | seq( 'one' ) | seq( 'one' ) |
+------------+------------+------------+------------+
|        102 |       1002 |        103 |        104 |
+------------+------------+------------+------------+
1 row IN SET ( 0 .00 sec)