SQL Server:拆分记录 [英] SQL Server: split record

问题描述

我有一个这样的表:

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:

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

如何仅使用 SQL服务器来做到这一点?

How do I do this using SQL server only?

谢谢

推荐答案

首先，您需要一个split函数，该函数可以让您确定结果中的顺序.这是使用IDENTITY列

First, you need a split function that can allow you to determine order within the result. This is a multi-statement TVF which uses an IDENTITY column

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

(如果您有一个Numbers表，则可以使用它代替子查询，这还将使您可以在函数的定义中添加WITH SCHEMABINDING，这可能会带来性能上的好处.)

(If you have a Numbers table, you can use that instead of the subquery, and this will also allow you to add WITH SCHEMABINDING to the function's definition, which provides potential performance benefits.)

使用该功能后，此处给出了您提供的数据和所需结果的示例用法:

With the function in place, here is sample usage given the data you've provided and desired results:

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

这假定您具有某种验证/强制执行，即check1和check2列中的对应值将始终具有相同数量的值.它还假定任何check1/check2值都不会超过7,000个字符(同样，Numbers表可以帮助使其更灵活).

This assumes that you have some kind of validation / enforcement that corresponding values in check1 and check2 columns will always have the same number of values. It also assumes any check1 / check2 value will not exceed about 7,000 characters (again a Numbers table can help make that more flexible).

编辑

在AndriyM发表评论后，我想返回并重新访问它，主要是为了提供上述功能的一个版本，该版本可以在不使用多语句TVF的情况下工作.这使用了安德里(Andriy)的想法ROW_NUMBER().

After AndriyM's comments I wanted to come back and re-visit this, mostly to supply a version of the above function which works without using a multi-statement TVF. This uses Andriy's idea ROW_NUMBER() could be used.

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

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