SQL Server:拆分记录

Question

我有这样一张桌子:

account   |   check1          |   check2
1         |   100]200]300     |   101]209]305
2         |   401]502         |   404]511
3         |   600             |   601

我想将记录分成这样的东西:

account   |   check1     |   check2
1         |   100        |   101
1         |   200        |   209
1         |   300        |   305
2         |   401        |   404
2         |   502        |   511
.         |     .        |    .
.         |     .        |    .
.         |     .        |    .

如何仅使用SQL Server执行此操作？

谢谢,

Answer 1

首先,您需要一个分割函数,可以让您确定结果中的顺序.这是一个使用IDENTITY列的多语句TVF

CREATE FUNCTION dbo.SplitStrings
(
    @List       NVARCHAR(MAX),
    @Delimiter  NVARCHAR(255)
)
RETURNS @t TABLE(ID INT IDENTITY(1,1), Item INT)
AS
BEGIN
    INSERT @t(Item) SELECT SUBSTRING(@List, Number, 
        CHARINDEX(@Delimiter, @List + @Delimiter, Number) - Number)
    FROM (SELECT ROW_NUMBER() OVER (ORDER BY [object_id])
        FROM sys.all_objects) AS n(Number)
    WHERE Number <= CONVERT(INT, LEN(@List))
        AND SUBSTRING(@Delimiter + @List, Number, 1) = @Delimiter
    ORDER BY Number OPTION (MAXDOP 1);

    RETURN;
END
GO

(如果您有Numbers表,则可以使用它而不是子查询,这也允许您将WITH SCHEMABINDING添加到函数的定义中,这可以提供潜在的性能优势.)

有了这个功能,根据您提供的数据和期望的结果,这里是样本用法:

DECLARE @x TABLE(account INT, check1 NVARCHAR(1000), check2 NVARCHAR(1000));

INSERT @x SELECT 1, '100]200]300','101]209]305'
UNION ALL SELECT 2, '401]502','404]511'
UNION ALL SELECT 3, '600','601'
UNION ALL SELECT 4, '205]104','304]701'; -- I added this sanity check

SELECT account, check1 = s1.Item, check2 = s2.Item
FROM @x AS x
CROSS APPLY dbo.SplitStrings(x.check1, ']') AS s1
CROSS APPLY dbo.SplitStrings(x.check2, ']') AS s2
WHERE s1.ID = s2.ID
ORDER BY account, s1.ID;

结果:

account  check1  check2
-------  ------  ------
1        100     101
1        200     209
1        300     305
2        401     404
2        502     511
3        600     601
4        205     304
4        104     701

这假设您有某种验证/强制执行,check1和check2列中的相应值将始终具有相同数量的值.它还假设任何check1/check2值不会超过大约7,000个字符(同样,Numbers表可以帮助使其更灵活).

编辑

在AndriyM的评论之后,我想回来重新访问它,主要是为了提供上述功能的一个版本,它可以在不使用多语句TVF的情况下工作.这使用Andriy的想法ROW_NUMBER()可以使用.

CREATE FUNCTION dbo.SplitStrings
(
    @List       NVARCHAR(MAX),
    @Delimiter  NVARCHAR(255)
)
RETURNS TABLE
AS
    RETURN (SELECT Number = ROW_NUMBER() OVER (ORDER BY Number),
        Item FROM (SELECT Number, Item = LTRIM(RTRIM(SUBSTRING(@List, Number, 
        CHARINDEX(@Delimiter, @List + @Delimiter, Number) - Number)))
    FROM (SELECT ROW_NUMBER() OVER (ORDER BY [object_id])
        FROM sys.all_objects) AS n(Number)
    WHERE Number <= CONVERT(INT, LEN(@List))
        AND SUBSTRING(@Delimiter + @List, Number, 1) = @Delimiter
    ) AS y);
GO