group by 和countselect count(type) from product group by type结果统计出来的是每组的个数（多行结果）想
group by 和count select count(type) from product group by type 结果统计出来的是每组的个数（多行结果） 想统计有多少种类型（单一结果）要怎么写？ 除了这种写法，单一语句能完成吗？ select count(1) from (select count(type) from product group by type)
[解决办法] select count(distinct type) from product [解决办法]
