sql - 按 XML 的不同大小写排序

Question

SQL Fiddle

SQL Server 2012 架构设置:

CREATE TABLE Course
(
     CourseID INT IDENTITY(1,1)
    ,CourseName NVARCHAR(20)
)

CREATE TABLE Session
(
     SessionID INT IDENTITY(1,1)
    ,CourseID  INT NULL
)

CREATE TABLE SessionTime
(
    ,SessionID INT
    ,DayOfWeek TINYINT --Sunday(0), Monday(1), ..., Saturday(6)
)

INSERT INTO COURSE(CourseName) VALUES('Science 10'), ('Bio 30')
INSERT INTO Session(CourseID) VALUES(1), (2)

INSERT INTO SessionTime(SessionID, DayOfWeek)
VALUES(1, 5), (1, 0), (1, 0), (1, 0), (1, 2), (1, 2), (1, 4),
      (2, 1), (2, 3)

查询:

SELECT   C.CourseName
        ,S.SessionID
        ,STUFF(
                (SELECT DISTINCT ', ' + CASE 
                                            WHEN ST.DayOfWeek = 0 THEN 'Su'
                                            WHEN ST.DayOfWeek = 1 THEN 'M'
                                            WHEN ST.DayOfWeek = 2 THEN 'T'
                                            WHEN ST.DayOfWeek = 3 THEN 'W'
                                            WHEN ST.DayOfWeek = 4 THEN 'Th'
                                            WHEN ST.DayOfWeek = 5 THEN 'F'
                                            WHEN ST.DayOfWeek = 6 THEN 'Sa'
                                        END
                FROM SessionTime ST
                WHERE ST.SessionID = S.SessionID
                --ORDER BY DayOfWeek
                FOR XML PATH (''))
            ,1,2,'') AS DaysOfWeek
FROM Session S
INNER JOIN Course C on S.CourseID = C.CourseID

Results :

| COURSENAME | SESSIONID |   DAYSOFWEEK |
|------------|-----------|--------------|
| Science 10 |         1 | F, Su, T, Th |
|     Bio 30 |         2 |         M, W |

期望的结果:

| COURSENAME | SESSIONID |   DAYSOFWEEK |
|------------|-----------|--------------|
| Science 10 |         1 | Su, T, Th, F | *Order of DaysOfWeek has changed.
|     Bio 30 |         2 |         M, W |

我想在将 DayOfWeek (Su,M,T,W,Th,F,Sa) STUFF 全部放在一起之前订购它们，但我的尝试导致了以下错误:

ORDER BY items must appear in the select list if SELECT DISTINCT is specified.

我试过以下方法:

• ORDER BY 1 按字母顺序排列日期，而不是 (Su,M,T,W,Th,F,Sa)
• ORDER BY DayOfWeek 导致上述错误消息
• ORDER BY DayOfWeekCase 添加一个 AS DayOfWeekCase 到 CASE 的 END 但这改变了方式 FOR XML 返回天数

如何在 STUFF 合并之前订购 DayOfWeek？

谢谢!

Answer 1

不要使用 DISTINCT，请尝试使用 GROUP BY。然后，您可以执行 ORDER BY DayOfWeek。

SELECT   C.CourseName
        ,S.SessionID
        ,STUFF(
                (SELECT ', ' + CASE 
                                            WHEN ST.DayOfWeek = 0 THEN 'Su'
                                            WHEN ST.DayOfWeek = 1 THEN 'M'
                                            WHEN ST.DayOfWeek = 2 THEN 'T'
                                            WHEN ST.DayOfWeek = 3 THEN 'W'
                                            WHEN ST.DayOfWeek = 4 THEN 'Th'
                                            WHEN ST.DayOfWeek = 5 THEN 'F'
                                            WHEN ST.DayOfWeek = 6 THEN 'Sa'
                                        END
                FROM SessionTime ST
                WHERE ST.SessionID = S.SessionID
                GROUP BY st.DayOfWeek
                ORDER BY DayOfWeek              
                FOR XML PATH (''))
            ,1,2,'') AS DaysOfWeek
FROM Session S
INNER JOIN Course C on S.CourseID = C.CourseID