SQL Server含逗号分隔的数据匹配维表

Posted 2021-02-13 农村的码农

日常有时候导出数据需求时，数据列会遇到带有分隔符的ID，但又需要匹配维表（如下图所示）将ID变成名称。

这种情况可以采用“分隔-匹配-合并”的方法

 

 

具体代码为： 

 

-- 准备工作1：创建事实表数据
CREATE TABLE #StudentSubject 
(
StuID INT IDENTITY(1,1) NOT NULL,
StuSubject VARCHAR(500) NOT NULL
)
INSERT INTO #StudentSubject(StuSubject) VALUES (\'1\')
INSERT INTO #StudentSubject(StuSubject) VALUES (\'2\')
INSERT INTO #StudentSubject(StuSubject) VALUES (\'2,3\')
INSERT INTO #StudentSubject(StuSubject) VALUES (\'2,3,4\')
INSERT INTO #StudentSubject(StuSubject) VALUES (\'1,2,3,4\')
INSERT INTO #StudentSubject(StuSubject) VALUES (\'4\')


-- 准备工作2：创建维表数据
CREATE TABLE #D_Subject 
(
SubjectID INT IDENTITY(1,1) NOT NULL,
SubjectName VARCHAR(500) NOT NULL
)

INSERT INTO #D_Subject(SubjectName) VALUES (\'语文\')
INSERT INTO #D_Subject(SubjectName) VALUES (\'数学\')
INSERT INTO #D_Subject(SubjectName) VALUES (\'英语\')
INSERT INTO #D_Subject(SubjectName) VALUES (\'体育\')


SELECT * FROM #StudentSubject
SELECT * FROM #D_Subject
;

-- 1分离：将逗号分隔的StuSubject分离匹配StudentSubject获取标签
WITH CetSubject AS 
(
SELECT StuID,
       CAST(LEFT(StuSubject, CHARINDEX(\',\', StuSubject + \',\') - 1) AS NVARCHAR(100)) SubjectID,
       CAST(STUFF(StuSubject + \',\', 1, CHARINDEX(\',\', StuSubject + \',\'), \'\') AS NVARCHAR(100)) Split
  FROM #StudentSubject
 UNION ALL
SELECT StuID,
       CAST(LEFT(Split, CHARINDEX(\',\', Split) - 1) AS NVARCHAR(100)) SIds,
       CAST(STUFF(Split, 1, CHARINDEX(\',\', Split), \'\') AS NVARCHAR(100)) Split
  FROM CetSubject
 WHERE split > \'\'
)
-- 2匹配 将分离后的数据逐行与维表匹配
SELECT CS.StuID,
       DS.SubjectName
  INTO #CetSubjectName
  FROM CetSubject CS
  LEFT JOIN #D_Subject DS ON DS.SubjectID = CS.SubjectID 
 WHERE CS.SubjectID <> \'\'
OPTION (MAXRECURSION 0);


-- 3合并 将与维表匹配的结果用逗号分隔合并还原
SELECT StuID,
       STUFF((SELECT \',\' + T.SubjectName FROM #CetSubjectName T WHERE T.StuID = T2.StuID FOR XML PATH(\'\')),1,1,\'\') SubjectName
  FROM #CetSubjectName t2
 GROUP BY StuID

DROP TABLE #D_Subject
DROP TABLE #StudentSubject
DROP TABLE #CetSubjectName