如何解决在用特殊字符分隔的表中拆分列值
我有一个看起来像这样的表:
Table 1
+----+--------+----------+
| ID | Name | SIZE |
+----+--------+----------+
| 1 | Style1 | S,M,L,XL |
+----+--------+----------+
我需要遍历整个表并将其加载到另一个如下所示的表中,而无需使用SPLIT_STRING
,而我们正在使用没有该功能的SQL Server 2012。
我还知道将插入到新表中的最大值将为100列宽。我对SQL还是很陌生,对功能以及如何使用它们不太满意。
Table 2
+----+--------+-------+-------+-------+-------+-----+-------+
| ID | NAME | SIZE1 | SIZE2 | SIZE3 | SIZE4 | ... | SIZEN |
+----+--------+-------+-------+-------+-------+-----+-------+
| 1 | Style1 | S | M | L | XL | | |
+----+--------+-------+-------+-------+-------+-----+-------+
谢谢
解决方法
由于您对Sql Server 2012感到困惑,因此可以使用一些XML语法。
这是应该帮助您的代码示例:
DECLARE @mockup TABLE (
[id] INT,[Name] VARCHAR(max),[Size] VARCHAR(max)
);
INSERT INTO @mockup
VALUES (
1,'Style','S,M,L,XL'
)
;WITH Splitted
AS (
SELECT [id],[Name],[Size],CAST('<x>' + REPLACE([Size],','</x><x>') + '</x>' AS XML) AS Parts
FROM @mockup
)
SELECT [id],Parts.value(N'/x[1]','varchar(5)') AS Column_1,Parts.value(N'/x[2]','varchar(5)') AS Column_2,Parts.value(N'/x[3]','varchar(5)') AS Column_3,Parts.value(N'/x[4]','varchar(5)') AS Column_4,Parts.value(N'/x[5]','varchar(5)') AS Column_5,Parts.value(N'/x[6]','varchar(5)') AS Column_6
--and so on until column 100
FROM Splitted;
结果:
基本上,以上代码将Size
列的内容转换为xml片段:
<x>S</x><x>M</x><x>L</x><x>XL</x>
然后,您可以使用value()
xml方法(更多信息here)提取不同列中的每个值。
最简单的方法是动态SQL,尤其是在大小列数变化的情况下。这是我放在一起可以在SSMS中运行的示例。它采用了@Andrea提到的某些相同原理并对其进行了扩展。
SET NOCOUNT ON;
DECLARE @Sizes TABLE ( Id INT,Name VARCHAR(50),Sizes VARCHAR(50) );
INSERT INTO @Sizes ( Id,Name,Sizes ) VALUES
( 1,'Style1',XL');
DECLARE @dynamic_sql VARCHAR(MAX);
SELECT @dynamic_sql = 'SELECT '
+ CAST ( [Id] AS VARCHAR(10) ) + ' AS [ID],'
+ '''' + [Name] + ''' AS [NAME],'
+ List.Cols + ';'
FROM @Sizes
OUTER APPLY (
SELECT CAST ( '<sizes><size>' + REPLACE ( Sizes,'</size><size>' ) + '</size></sizes>' AS XML ) SizeXml
) AS x
OUTER APPLY (
SELECT STUFF ( (
SELECT
',''' + Size + ''' AS [SIZE' + CAST ( SizeId AS VARCHAR(10) ) + ']' AS "text()"
FROM (
SELECT
ROW_NUMBER() OVER ( ORDER BY ( SELECT NULL ) ) AS SizeId,n.s.value ( '.','VARCHAR(50)' ) AS Size
FROM x.SizeXml.nodes('//sizes/size') n ( s )
) AS xml_list FOR XML PATH ('')
),1,2,'' ) AS Cols
) AS List
WHERE Id = 1;
-- Execute the dynamic SQL statement.
EXEC ( @dynamic_sql );
返回
+----+--------+-------+-------+-------+-------+
| ID | NAME | SIZE1 | SIZE2 | SIZE3 | SIZE4 |
+----+--------+-------+-------+-------+-------+
| 1 | Style1 | S | M | L | XL |
+----+--------+-------+-------+-------+-------+
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