sql语句问题,高手请进例如一个表中有多个种类的东西,每个种类又分1,2两种情况,统计每个种类这两种情况各是多少用sql统计,有什么好的解决方案么[解决办法]
select "种类", sum(case when "子类" = '1' then 1 else 0 end) as "子类1次数", sum(case when "子类" = '2' then 1 else 0 end) as "子类1次数" from tbl group by "种类";