是否可以在 SQL Server 中比较类似数据的行？我在表中有一个公司名称列，其中公司名称可能有些相似。以下是代表相同 4 家公司的不同 8 个值的示例：
ANDORRA WOODS
ANDORRA WOODS HEALTHCARE CENTER
ABC HEALTHCARE, JOB #31181
ABC HEALTHCARE, JOB #31251
ACTION SERVICE SALES, A SUBSIDIARY OF SINGER EQUIPMENT
ACTION SERVICE SALES, A SUBSIDIARY OF SINGER EQUIPMENT COMPANY
APEX SYSTEMS
APEX SYSTEMS, INC
我现在清理它的方法是使用谷歌优化，在那里我可以识别相似数据值的集群并将它们全部整合在一起。使用此示例，我只需要 4 个名称而不是 8 个名称，因此我需要用一个替换类似的名称，因为稍后我将为这些名称分配索引。任何帮助是极大的赞赏。
我有几个 UDF 是我前段时间从一些 VB 代码转换而来的，它接受 2 个 varchar() 并返回一个介于 0 和 100 之间的 int（0= 不相似，100= 相同），如果您感兴趣的话。
-- Description: Removes any special characters from a string
CREATE FUNCTION [dbo].[SimReplaceSpecial]
(
-- Add the parameters for the function here
@String varchar(max)
)
RETURNS varchar(max)
AS
BEGIN
-- Declare the return variable here
DECLARE @Result varchar(max) = ''
-- Add the T-SQL statements to compute the return value here
DECLARE @Pos int = 1
DECLARE @Asc int
DECLARE @WorkingString varchar(max)
SET @WorkingString = upper(@String)
WHILE @Pos <= LEN(@WorkingString)
BEGIN
SET @Asc = ascii(substring(@WorkingString,@Pos,1))
If (@Asc >= 48 And @Asc <= 57) Or (@Asc >= 65 And @Asc <= 90)
SET @Result = @Result + Char(@Asc)
SET @Pos = @Pos + 1
--IF @Pos + 1 > len(@String)
-- BREAK
--ELSE
-- CONTINUE
END
-- Return the result of the function
RETURN @Result
END
-- Description: DO NOT CALL DIRECTLY - Used by the Similar function
-- Finds longest common substring (other than single
-- characters) in String1 and String2, then recursively
-- finds longest common substring in left-hand
-- portion and right-hand portion. Updates the
-- cumulative score.
CREATE FUNCTION [dbo].[SimFindCommon]
(
-- Add the parameters for the function here
@String1 varchar(max),
@String2 varchar(max),
@Score int
)
RETURNS int
AS
BEGIN
-- Declare the return variable here
--DECLARE @Result int
DECLARE @Longest Int = 0
DECLARE @StartPos1 Int = 0
DECLARE @StartPos2 Int = 0
DECLARE @J Int = 0
DECLARE @HoldStr varchar(max)
DECLARE @TestStr varchar(max)
DECLARE @LeftStr1 varchar(max) = ''
DECLARE @LeftStr2 varchar(max) = ''
DECLARE @RightStr1 varchar(max) = ''
DECLARE @RightStr2 varchar(max) = ''
-- Add the T-SQL statements to compute the return value here
SET @HoldStr = @String2
WHILE LEN(@HoldStr) > @Longest
BEGIN
SET @TestStr = @HoldStr
WHILE LEN(@TestStr) > 1
BEGIN
SET @J = CHARINDEX(@TestStr,@String1)
If @J > 0
BEGIN
--Test string is sub-set of the other string
If Len(@TestStr) > @Longest
BEGIN
--Test string is longer than previous
--longest. Store its length and position.
SET @Longest = Len(@TestStr)
SET @StartPos1 = @J
SET @StartPos2 = CHARINDEX(@TestStr,@String2)
END
--No point in going further with this string
BREAK
END
ELSE
--Test string is not a sub-set of the other
--string. Discard final character of test
--string and try again.
SET @TestStr = Left(@TestStr, LEN(@TestStr) - 1)
END
--Now discard first char of test string and
--repeat the process.
SET @HoldStr = Right(@HoldStr, LEN(@HoldStr) - 1)
END
--Update the cumulative score with the length of
--the common sub-string.
SET @Score = @Score + @Longest
--We now have the longest common sub-string, so we
--can isolate the sub-strings to the left and right
--of it.
If @StartPos1 > 3 And @StartPos2 > 3
BEGIN
SET @LeftStr1 = Left(@String1, @StartPos1 - 1)
SET @LeftStr2 = Left(@String2, @StartPos2 - 1)
If RTRIM(LTRIM(@LeftStr1)) <> '' And RTRIM(LTRIM(@LeftStr2)) <> ''
BEGIN
--Get longest common substring from left strings
SET @Score = dbo.SimFindCommon(@LeftStr1, @LeftStr2,@Score)
END
END
ELSE
BEGIN
SET @LeftStr1 = ''
SET @LeftStr2 = ''
END
If @Longest > 0
BEGIN
SET @RightStr1 = substring(@String1, @StartPos1 + @Longest, LEN(@String1))
SET @RightStr2 = substring(@String2, @StartPos2 + @Longest, LEN(@String2))
If RTRIM(LTRIM(@RightStr1)) <> '' And RTRIM(LTRIM(@RightStr2)) <> ''
BEGIN
--Get longest common substring from right strings
SET @Score = dbo.SimFindCommon(@RightStr1, @RightStr2,@Score)
END
END
ELSE
BEGIN
SET @RightStr1 = ''
SET @RightStr2 = ''
END
-- Return the result of the function
RETURN @Score
END
-- Description: Compares two not-empty strings regardless of case.
-- Returns a numeric indication of their similarity
-- (0 = not at all similar, 100 = identical)
CREATE FUNCTION [dbo].[Similar]
(
-- Add the parameters for the function here
@String1 varchar(max),
@String2 varchar(max)
)
RETURNS int
AS
BEGIN
-- Declare the return variable here
DECLARE @Result int
DECLARE @WorkingString1 varchar(max)
DECLARE @WorkingString2 varchar(max)
-- Add the T-SQL statements to compute the return value here
if isnull(@String1,'') = '' or isnull(@String2,'') = ''
SET @Result = 0
ELSE
BEGIN
--Convert each string to simplest form (letters
--and digits only, all upper case)
SET @WorkingString1 = dbo.SimReplaceSpecial(@String1)
SET @WorkingString2 = dbo.SimReplaceSpecial(@String2)
If RTRIM(LTRIM(@WorkingString1)) = '' Or RTRIM(LTRIM(@WorkingString2)) = ''
BEGIN
--One or both of the strings is now empty
SET @Result = 0
END
ELSE
BEGIN
If @WorkingString1 = @WorkingString2
BEGIN
--Strings are identical
SET @Result = 100
END
ELSE
BEGIN
--Find all common sub-strings
SET @Result = dbo.SimFindCommon(@WorkingString1, @WorkingString2,0)
--We now have the cumulative score. Return this
--as a percent of the maximum score. The maximum
--score is the average length of the two strings.
SET @Result = @Result * 200 / (Len(@WorkingString1) + Len(@WorkingString2))
END
END
END
-- Return the result of the function
RETURN @Result
END
--Usage--------------------------------------------------------------------
--Call the "Similar" Function only
SELECT dbo.Similar('ANDORRA WOODS','ANDORRA WOODS HEALTHCARE CENTER')
--Result = 60
SELECT dbo.Similar('ABC HEALTHCARE, JOB #31181','ABC HEALTHCARE, JOB #31251')
--Result = 85
SELECT dbo.Similar('ACTION SERVICE SALES, A SUBSIDIARY OF SINGER EQUIPMENT','ACTION SERVICE SALES, A SUBSIDIARY OF SINGER EQUIPMENT COMPANY')
--Result = 92
SELECT dbo.Similar('APEX SYSTEMS','APEX SYSTEMS, INC')
--Result = 88
SSIS/数据工具有一个模糊分组转换，在这种情况下非常有用。它实际上并没有对您的数据进行分组，而是为您提供相似性分数，您可以使用这些分数来确定何时应将项目分组在一起。
那里有很多教程，这里有一个： 模糊分组转换