Question

我有以下数据

我想将列转换为行

我使用了以下Query ::

Select Distinct [ApplicantID],

Split.a.value('.', 'VARCHAR(100)') AS Subjects, 

hoursperweek,[Days],[Time] 

From ( Select 

       Cast ('<M>' + REPLACE([Subjects], ',', '</M><M>') + '</M>' AS XML) 

     AS Subjects , ApplicantID, hoursperweek,[Days],[Time] 

     From  [dbo].[Progrm])

AS A CROSS APPLY Subjects.nodes ('/M') AS Split(a)

它给我以下结果

但是我想分开主题，每周几小时，几天，几天。我怎么能这样做？

ApplicantID  Subjects  HoursPerWeek   Days       Time
1             a          12           Sun      12:45:12
1             b          25           Mon      14:45:12

Answer 1

这是一个将逗号分隔值拆分为行

的函数

CREATE FUNCTION dbo.Splitstrings (@List      NVARCHAR(MAX),
                                  @Delimiter NVARCHAR(255))
RETURNS @split_tab TABLE (
  RN        INT IDENTITY(1, 1),
  SPLIT_VAL VARCHAR(100))
WITH SCHEMABINDING
AS
  BEGIN ;
      ;WITH E1(N)
           AS (SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
               SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
               SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1),
           E2(N) AS (SELECT 1 FROM E1 a,E1 b),
           E4(N) AS (SELECT 1 FROM E2 a, E2 b),
           E42(N) AS (SELECT 1 FROM E4 a, E2 b),
           cteTally(N)
           AS (SELECT 0
               UNION ALL
               SELECT TOP (Datalength(Isnull(@List, 1))) Row_number()OVER (
                                                             ORDER BY (SELECT NULL))
               FROM   E42),
           cteStart(N1)
           AS (SELECT t.N + 1
               FROM   cteTally t
               WHERE  ( Substring(@List, t.N, 1) = @Delimiter
                         OR t.N = 0 ))
      INSERT INTO @split_tab
      SELECT SPLIT_VAL= Substring(@LIST, S.N1, Isnull(NULLIF(Charindex(@DELIMITER, @LIST, S.N1), 0) - S.N1, 8000))
      FROM   CTESTART S;

      RETURN
  END

现在分割数据的丑陋代码

;WITH data
     AS (SELECT 1                   ApplicantID,
                'a,b'               Subjects,
                '12,25'             HoursPerWeek,
                'sun,mon'           Days,
                '12:45:12,14:45:12' Time),
     sub
     AS (SELECT RN,
                ApplicantID,
                Subjects=SPLIT_VAL
         FROM   data
                CROSS apply Splitstrings (Subjects, ',')),
     HPW
     AS (SELECT RN,
                ApplicantID,
                HoursPerWeek=SPLIT_VAL
         FROM   data
                CROSS apply Splitstrings (HoursPerWeek, ',')),
     Days
     AS (SELECT RN,
                ApplicantID,
                Days=SPLIT_VAL
         FROM   data
                CROSS apply Splitstrings (Days, ',')),
     Time
     AS (SELECT RN,
                ApplicantID,
                Time=SPLIT_VAL
         FROM   data
                CROSS apply Splitstrings (Time, ','))
SELECT D.APPLICANTID,
       S.SUBJECTS,
       H.HOURSPERWEEK,
       DA.DAYS,
       T.TIME
FROM   DATA D
       FULL OUTER JOIN SUB S
                    ON D.APPLICANTID = S.APPLICANTID
       FULL OUTER JOIN HPW H
                    ON D.APPLICANTID = H.APPLICANTID
                       AND H.RN = S.RN
       FULL OUTER JOIN DAYS DA
                    ON D.APPLICANTID = DA.APPLICANTID
                       AND DA.RN = COALESCE(S.RN, H.RN)
       FULL OUTER JOIN TIME T
                    ON D.APPLICANTID = T.APPLICANTID
                       AND T.RN = COALESCE(S.RN, H.RN, DA.RN)

<强>结果：

╔═════════════╦══════════╦══════════════╦══════╦══════════╗
║ APPLICANTID ║ SUBJECTS ║ HOURSPERWEEK ║ DAYS ║   TIME   ║
╠═════════════╬══════════╬══════════════╬══════╬══════════╣
║           1 ║ a        ║           12 ║ sun  ║ 12:45:12 ║
║           1 ║ b        ║           25 ║ mon  ║ 14:45:12 ║
╚═════════════╩══════════╩══════════════╩══════╩══════════╝

这就是我们永远不应该将逗号分隔值存储到单个列中的原因。当你想解析数据时，事情变得困难，我们需要这些丑陋的代码来解析数据

多个CSV列到行SQL查询

1 个答案: