Question

在MySql数据库中有AM_COURSE

UserId      CourseName   course_desc
  101          java        sometext...
  102          mysql       sometext....
   :

AM_TIMETABLE表

UserId        Date_Time
 101        2012-08-08 04:00:00 
 102        2012-08-15 10:00:00
 103        2012-08-18 09:00:00
 104        2012-08-24 05:00:00

我的问题是，我正在传递开始日期和结束日期以及CourseName然后我希望以这种方式获取UserId我写了查询

select UserId,CourseName,course_desc from AM_COURSE where name='java' and UserId=(SELECT UserId FROM AM_TIMETABLE WHERE `Date_Time` BETWEEN '2012-08-07 00:00:00' AND '2012-08-20 00:00:00')

然后我将获得101 UserId值。但我收到错误，因为内部查询给出两个id ... please help

Answer 1

重命名每个表中的ID可能会有所帮助，可能是COURSE_ID和TIMETABLE_ID。在这种情况下，您还可以创建一个包含所有用户信息的表，例如姓名，电子邮件等。

一旦正确设置了表格，主键/外键配对将有助于连接表格并将数据输出为可想到的格式。

Answer 2

你可以join这两个表：

SELECT  a.UserID
FROM    AM_COURSE a
            INNER JOIN AM_TIMETABLE b
                ON a.UserID = b.USerID
WHERE   a.CourseName = 'java' AND
        b.Date_Time BETWEEN '2012-08-07 00:00:00' AND '2012-08-20 00:00:00'

Answer 3

SELECT c.UserId
FROM   AM_COURSE c
  JOIN AM_TIMETABLE t 
    ON c.UserId = t.UserId
WHERE c.name = 'java'
  AND t.Date_Time BETWEEN '2012-08-07 00:00:00' AND '2012-08-20 00:00:00'

Answer 4

这个怎么样

select c.UserId,CourseName,course_desc from AM_COURSE c where name='java' and c.UserId=(SELECT t.UserId FROM AM_TIMETABLE t WHERE `Date_Time` BETWEEN '2012-08-07 00:00:00' AND '2012-08-20 00:00:00')

Answer 5

如果您的内部查询返回的结果超过1（当然这对您的方案有效），那么您不应该使用 IN 子句吗？

select UserId
,CourseName
,course_desc 
from AM_COURSE 
where name='java' and UserId in (
    SELECT UserId 
    FROM AM_TIMETABLE 
    WHERE `Date_Time` BETWEEN '2012-08-07 00:00:00' AND '2012-08-20 00:00:00'
)

如何在两个表之间获取ID？

5 个答案: