原来mysql不支持外键，要用InnoDB才可以..

原来一直用postgresql,最近接触到了mysql(5.0.20),它默认是MyISAM引擎，竟然不支持外键，后来才知道要用InnoDB引擎才能支持..
create database test;
use test;
CREATE TABLE userinfo (
   userid character(8)  primary key,
  temp character(8)

  )Type=INNODB  CHARACTER SET utf8;

CREATE TABLE commenttest(
    userid character(8),
    comment   character varying(200),
      foreign key(userid) references userinfo(userid) on delete cascade)
Type= INNODB CHARACTER SET utf8;

insert into userinfo values("06000017","aaaa");
insert into userinfo values("06000020","bbbb");

insert into commenttest values("06000017","cccccc");
insert into commenttest values("06000020","ddddd");