Mysql5.7.21 Navicat触发器创建

create trigger m_trigger after update on table1 
for each row
begin
if( old.status!= new.status)
then
select count(id) from table1 where stats='y' into @ycount;

select max(num) from table2 into @maxycount;
if( @ycount> @maxycount)
then
insert into table2 (num) select count(1) from table1 b where b.statu='y';
end if;
end if;
end

注：mysql中变量不用事先声明，用时直接‘@变量名’使用。

1、set @num=1;  set @num:=1; 

2、select count(id) from table1 where stats='y' into @ycount;