尝试加入多个表的问题

Question

有关学校在学年中期有两种不同的方式来提拔资优学生。第一个简单地将他们提升到下一个年级；另一种是将他们同时“双录取”到两个年级。然而，当我们给学生他们的时间表时，我们只想报告学生注册的最高年级。查询应该return表示任何日期的信息。如果您要运行此查询“01/15/2013”的示例数据，它将 return:

| name  | grade | className |
|-------|-------|-----------|
| Adam  | 8     | Science   |
| Adam  | 8     | English   |
| Alice | 7     | English   |
| Alice | 7     | History   |
| Jack  | 7     | English   |
| Jack  | 7     | Math      |

表格的结构如下：

CREATE TABLE dbo.[Class]
(
    classID INT NOT NULL PRIMARY KEY,
    name VARCHAR(50)
)

CREATE TABLE dbo.[Person]
(
    personID INT NOT NULL PRIMARY KEY,
    name VARCHAR(50),
    parentID1 INT,
    parentID2 INT,
    gender VARCHAR(10)
)


CREATE TABLE dbo.AttendanceRecord
(
    attendanceID INT IDENTITY(1,1) NOT NULL PRIMARY KEY,
    personID INT,
    classID INT,
    [date] SMALLDATETIME,
    CONSTRAINT FK_attendancePerson FOREIGN KEY (personID) REFERENCES Person(personID),
    CONSTRAINT FK_attendanceClass FOREIGN KEY (classID) REFERENCES Class(classID)
)


CREATE TABLE dbo.Schedule
(
    personID INT,
    classID INT,
    CONSTRAINT FK_schedulePerson FOREIGN KEY (personID) REFERENCES Person(personID),
    CONSTRAINT FK_scheduleClass FOREIGN KEY (classID) REFERENCES Class(classID)
)

CREATE TABLE dbo.Enrollment 
(
    personID INT,
    startDate SMALLDATETIME,
    endDate SMALLDATETIME,
    grade INT,
    CONSTRAINT FK_enrollmentPerson FOREIGN KEY (personID) REFERENCES Person(personID)
)

这是我正在使用的样本数据：

INSERT INTO dbo.AttendanceRecord
SELECT 25,123,'03/21/2013'
UNION
SELECT 25,456,'03/21/2013'
UNION
SELECT 25,789,'03/21/2013'
UNION
SELECT 13,147,'03/21/2013'
UNION
SELECT 25,123,'03/22/2013'
UNION
SELECT 82,147,'03/22/2013'
UNION
SELECT 82,456,'03/22/2013'
UNION
SELECT 13,147,'03/23/2013'
UNION
SELECT 25,456,'03/23/2013'
UNION
SELECT 13,456,'03/24/2013'
UNION
SELECT 25,456,'03/28/2013'


INSERT INTO dbo.Class
SELECT 123, 'Math'
UNION
SELECT 456, 'English'
UNION
SELECT 789, 'History'
UNION 
SELECT 258, 'Lunch'
UNION
SELECT 147, 'Science'

INSERT INTO dbo.Person
SELECT 25, 'Jack', 255, NULL, 'Male'
UNION
SELECT 13, 'Jill', 100, 101, 'Female'
UNION
SELECT 82, 'Adam', NULL, 200, 'Male'
UNION
SELECT 100, 'Jeff', NULL, NULL, 'Male'
UNION
SELECT 101, 'June', NULL, NULL, 'Female'
UNION
SELECT 200, 'Shirley', NULL, NULL, 'Female'
UNION
SELECT 155, 'Alice', 255, NULL, 'Female'
UNION
SELECT 255, 'Tom', NULL, NULL, 'Male'
UNION
SELECT 19, 'Jake', 100,101, 'Male'


INSERT INTO dbo.Schedule
SELECT 25,123
UNION
SELECT 25,456
UNION
SELECT 25,789
UNION
SELECT 13,147
UNION
SELECT 82,147
UNION
SELECT 82,456
UNION
SELECT 13,456
UNION
SELECT 19,123
UNION
SELECT 19,789
UNION
SELECT 155,456
UNION
SELECT 155,789


INSERT INTO dbo.Enrollment
SELECT 25, '09/01/2012','05/31/2013', 7
UNION
SELECT 25, '03/01/2013','05/31/2013', 8
UNION
SELECT 13, '09/01/2012','05/31/2013', 7
UNION
SELECT 82, '09/01/2012', '12/31/2012', 7
UNION
SELECT 82, '01/01/2013', '05/31/2013', 8
UNION
SELECT 19, '09/01/2012', '05/31/2013', 8
UNION
SELECT 155, '09/01/2012','05/31/2013', 7

我曾尝试使用多个连接来实现此查询，但似乎没有任何效果。它要么显示大量我不想要的结果列表，要么抛出错误。

SELECT P.name, E.grade, C.name AS className
FROM Schedule AS S
JOIN Class AS C ON C.classid = S.classid
JOIN Person AS P ON P.personid = S.personid
JOIN Enrollment AS E ON E.personid = P.personid

现在我知道这不是我需要的，但它是我的起点。不确定这是否是正确的前进方向

Answer 1

您的数据不明确，结果提供issues.however查询是

SELECT P.NAME,
       C.NAME,
       grade
FROM   (SELECT personid,
               classid,
               Max(grade) grade
        FROM  (SELECT E.personid,
                      A.classid,
                      E.grade
               FROM   (SELECT personid,
                              classid,
                              Min([date]) startDate,
                              Max([date]) endDate
                       FROM   AttendanceRecord
                       GROUP  BY personid,
                                 classid) A
                      JOIN Enrollment E
                        ON E.personid = A.personid
              ---AND A.startDate=E.startDate AND A.endDate=E.endDate
--Data is not clear and it provide no result
              ) AA
        GROUP  BY personid,
                  classid)AB
       JOIN Class C
         ON C.classid = AB.classid
       JOIN Person P
         ON P.personid = AB.personid

尝试加入多个表的问题

Issues trying to join multiple tables

sql

sql-server

join