创建一个触发器新增字段的时候设置某个字段的值

drop trigger if EXISTS tr_userinfo_enterdate;
CREATE trigger tr_userinfo_enterdate 
before insert on userinfo 
for each row
begin
   set new.enterdate=now();
end

语法结构:

create trigger trigger_name

before||after  update||insert on table_name

for each row

begin

   sql statements

end