在两个表之间获取不同的记录（MySQL）

Question

在两个表之间获取不同的记录（MySQL）

phpmysqlsql

4

我需要展示“预定与实际”报告，该报告展示了持有学校出勤数据的MySQL数据库中两个表之间的差异。

我有两个称为Booking和Attendance的表。

表中存储的数据如下：

Booking表：

Id Student   Date     IsAbsent
1  John      20160216    1 //NO
2  Bob       20160217    1 //NO
3  Zara      20160218    1 //NO

出席记录。

Id Student    Date     IsAbsent
1  John       20160216    0 //YES
2  Bob        20160217    0 //YES
3  Mary       20160217    1 //NO

基本上，我想将输出显示为：

。

**Id | Student | Day_1 | Day_2  |  Day_3**
 ==== ========= ======  =======  ======
   1 | John    |ABSENT | NULL   | NULL 
   2 | Bob     |NULL   |ABSENT  | NULL
   3 | Mary    |NULL   |NEW     | NULL
   4 | Zara    |DELETED|NULL    | NULL

缺席在预订表中，约翰被标记为1（假），但在出勤表中，他被标记为0（是），因此我想显示为“缺席”。

新增玛丽仅在出勤表中有记录，但在预订表中没有记录。

已删除 萨拉最初被预订，并在预订表中，但不在出勤表中。

我已经创建了 SQL Fiddle 的模式和查询，但它总是返回空值。

我的 SQL 查询如下所示...

 SELECT * FROM 
((SELECT
  a.Student as student,
   MAX( case
       when a.DropDate='20160216' && a.IsAbsent=0 && s.IsAbsent=1 then 'Absent'
       when (select count(*) from attendance where DropDate='20160216')=0 && (select count(*) from staging where DropDate='20160216')>0 then 'DELETED Booking'
       when (select count(*) from attendance where DropDate='20160216')>0 && (select count(*) from staging where DropDate='20160216')=0 then 'New Booking' 
       else ' ' end ) as 'day_1',
  MAX( case 
       when a.DropDate='20160217' && a.IsAbsent=0 && s.IsAbsent=1 then 'Absent'
       when (select count(*) from attendance where DropDate='20160217')=0 && (select count(*) from staging where DropDate='20160217')>0 then 'DELETED Booking'
       when (select count(*) from attendance where DropDate='20160217')>0 && (select count(*) from staging where DropDate='20160217')=0 then 'New Booking' 
       else ' '  end ) as 'day_2',
  MAX( case 
       when a.DropDate='20160218' && a.IsAbsent=0 && s.IsAbsent=1 then 'Absent'
       when (select count(*) from attendance where DropDate='20160218')=0 && (select count(*) from staging where DropDate='20160218')>0 then 'DELETED Booking'
       when (select count(*) from attendance where DropDate='20160218')>0 && (select count(*) from staging where DropDate='20160218')=0 then 'DELETED Booking' 
       else ' '  end ) as 'day_3'
FROM Attendance a LEFT JOIN Booking s on a.Student=s.Student
WHERE a.DropDate IN ('20160216','20160217','20160218')
   AND  NOT EXISTS 
      ( SELECT 1
        FROM Booking AS p
        WHERE p.Student = a.Student
          AND p.IsAbsent = a.IsAbsent
          AND p.DropDate = a.DropDate
      )
)
UNION 
(SELECT
  t.Student as student,
  MAX( case
       when t.DropDate='20160216' && a.IsAbsent=0 && t.IsAbsent=1 then 'Absent'
       when (select count(*) from attendance where DropDate='20160216')=0 && (select count(*) from staging where DropDate='20160216')>0 then 'DELETED Booking'
       when (select count(*) from attendance where DropDate='20160216')>0 && (select count(*) from staging where DropDate='20160216')=0 then 'New Booking' 
       else ' ' end ) as 'day_1',
  MAX( case 
       when a.DropDate='20160217' && a.IsAbsent=0 && t.IsAbsent=1 then 'Absent'
       when (select count(*) from attendance where DropDate='20160217')=0 && (select count(*) from staging where DropDate='20160217')>0 then 'DELETED Booking'
       when (select count(*) from attendance where DropDate='20160217')>0 && (select count(*) from staging where DropDate='20160217')=0 then 'New Booking' 
       else ' '  end ) as 'day_2',
  MAX( case 
       when a.DropDate='20160218' && a.IsAbsent=0 && t.IsAbsent=1 then 'Absent'
       when (select count(*) from attendance where DropDate='20160218')=0 && (select count(*) from staging where DropDate='20160218')>0 then 'DELETED Booking'
       when (select count(*) from attendance where DropDate='20160218')>0 && (select count(*) from staging where DropDate='20160218')=0 then 'DELETED Booking' 
       else ' '  end ) as 'day_3'
FROM Booking t LEFT JOIN attendance a on t.Student=a.Student
WHERE t.DropDate IN ('20160216','20160217','20160218')
  AND  NOT EXISTS 
      ( SELECT 1
        FROM Attendance AS u
        WHERE u.Student = t.Student
          AND u.IsAbsent = t.IsAbsent
          AND u.DropDate = t.DropDate
      )
)) tbl
ORDER BY  student

任何帮助都将不胜感激。

- snowflakes74

这很有趣。我正在管道中有一个类似的问题，正在跟进这个。 - chapskev

1个回答

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- St3an · Accepted Answer

我不确定你是否能在MySQL查询中输出内联布局，除非你使用存储过程...我不知道这对你是否可行，因为它的布局略有不同，但它可以工作：

(select s.Student,
       s.ClassRoom,
       s.DropDate,
       if(s.IsAbsent=1&&a.IsAbsent=0,'ABSENT','PRESENT')
from Staging s inner join Attendance a on a.Student = s.Student and a.ClassRoom = s.ClassRoom and a.DropDate = s.DropDate)
UNION ALL
(Select s.Student,
       s.ClassRoom,
       s.DropDate,
       'DELETED'
from Staging s left join Attendance a on a.Student = s.Student and a.ClassRoom = s.ClassRoom and a.DropDate = s.DropDate
where a.Student is null)
UNION ALL
(Select a.Student,
       a.ClassRoom,
       a.DropDate,
       'NEW'
from Staging s right join Attendance a on a.Student = s.Student and a.ClassRoom = s.ClassRoom and a.DropDate = s.DropDate
where s.Student is null)
order by Student, DropDate;