数据库面试题-胜负统计

数据库面试题-胜负统计

mysql 第一种解决方法

SELECT    datetime 日期,
         SUM(if(result='胜',1,0)) 胜,
         SUM(if(result='负',1,0)) 负
		from t_nba
		group by datetime

 

通用sql，使用left join完成

SELECT t.*,t2.fu from 
	(SELECT DISTINCT(t_nba.datetime) datetime, t1.sheng from t_nba
		LEFT JOIN
		(
			SELECT datetime , COUNT(*) as sheng from t_nba
				where result='胜' GROUP BY datetime
		) as t1
	on t_nba.datetime = t1.datetime
	) t LEFT JOIN
			(
			SELECT datetime , COUNT(*) as fu from t_nba
				where result='负' GROUP BY datetime
		) as t2
ON t.datetime = t2.datetime