mysql中如何统计某字段里某个字符的个数？

Question

如我的表order里有一个字段order_num，里面存的是一些订单号，形式如“od_135484315315431541541”，现在我要统计这个订单号有多少个8，如出现4个8就算中奖，请问如何把这些数据查找出来？

Answer 1

select length(order_num)-length(replace(order_num,'8',''))

Answer 2

select length(order_num)-length(replace(order_num,'8',''));
+1

Answer 3

明白了，正确的写法应该是
select * from order where length(order_num)-length(replace(order_num,'8','')) = 4
谢谢各位的回复。