sql语句中的多个where子句？

Question

我有一个简单的sessions表，如下所示：

   sid  watchtime
    1   01:07:00
    2   01:07:00
    3   01:34:00
    4   01:36:00
    5   01:36:00
    6   01:59:00
    7   01:59:00
    8   00:00:00
    9   00:00:00
    10  03:42:00
    11  00:16:00
    12  00:49:00
    13  00:55:00
    14  00:00:00
    15  00:05:00
    16  00:05:00

现在，我想显示观看时间>=5和观看时间<5计数。 我尝试了以下解决方案：

SELECT count(watchtime) as lessthan_five FROM sessions 
WHERE watchtime <=5 
AND count(watchtime) as morethan_five 
         from sessions WHERE watchtime >5";

我收到以下错误：

1064-您的SQL语法有误； 检查与您的MySQL服务器版本相对应的手册以获取正确的语法，以在第1行“在WHERE观看时间> = 5”的会话中使用“大于”

我的代码在做什么错？

Answer 1

您可以使用条件聚合来获得所需的结果，这是通过在数字上下文中使用MySQL将布尔值视为1或0来实现的：

SELECT SUM(watchtime <= '00:05:00') AS lessthan_five,
       SUM(watchtime >  '00:05:00') AS morethan_five
FROM sessions

输出：

lessthan_five   morethan_five
5               11

dbfiddle上的演示

Answer 2

如果您希望行的值超过五分钟，请执行以下操作：

SELECT COUNT(*) FROM sessions WHERE watchtime >= '00:05:00'
SELECT COUNT(*) FROM sessions WHERE watchtime < '00:05:00'

如果要获取小时数以外的分钟数的行数：

SELECT COUNT(*) FROM sessions WHERE MINUTE(watchtime) >= 5
SELECT COUNT(*) FROM sessions WHERE MINUTE(watchtime) < 5

同样，这将为您提供所有观看时间的计数，其中计数<> 5：

SELECT watchtime, COUNT(*) as Num
FROM sessions 
GROUP BY watchtime
HAVING COUNT(*) <> 5

您可以根据需要编辑子句。

Answer 3

你可以试试这个

   SELECT watchtime, count(watchtime) as lessthan_five FROM sessions 
   WHERE watchtime <=5 
   AND watchtime in ( select watchtime as morethan_five 
     from sessions group by `category_id` having `watchtime` >5);