Как сравнить похожие строки (неполное совпадение строк)?

CREATE FUNCTION fn_FuzzyCompareString(
@Stri1 varchar(250),
@Stri2 varchar(250),
@MaxLen int)
RETURNS float
AS
BEGIN

DECLARE @Str1 varchar(250), @Str2 varchar(250), @SCountVar int,
@SCountEq int, @LenStr int, @Res float
DECLARE @NumSymbStr2 int
DECLARE @Cnt1 int, @Cnt2 int
DECLARE @SubStr varchar(250)

SELECT
@LenStr=1,
@SCountVar=0 ,
@SCountEq=0,
@res=0

Set @Str1 = replace(LTRIM(RTRIM(upper(@Stri1))),'.',' ')
Set @Str2 = replace(LTRIM(RTRIM(upper(@Stri2))),'.',' ')

if ((@MaxLen <= 0) or (Len(@Str1)=0) or (Len(@Str2)=0))
Begin
Set @Res=0
End
else
begin
While (@LenStr<=@MaxLen)
BEGIN
Set @NumSymbStr2=1
Set @Cnt2=0

While ((@Cnt2+@LenStr)<=LEN(@Str2))
BEGIN

Set @SubStr = '%'+SUBSTRING(@Str2,@NumSymbStr2,@LenStr)+'%'
if (PATINDEX(@SubStr, @Str1)<>0)
begin
Set @SCountEq=@SCountEq+1
end

Set @SCountVar=@SCountVar+1
Set @NumSymbStr2=@NumSymbStr2+1
Set @Cnt2 = @Cnt2+1
END


Set @NumSymbStr2=1
Set @Cnt2=0

While ((@Cnt2+@LenStr)<=LEN(@Str1))
BEGIN

Set @SubStr = '%'+SUBSTRING(@Str1,@NumSymbStr2,@LenStr)+'%'
if (PATINDEX(@SubStr, @Str2)<>0)
begin
Set @SCountEq=@SCountEq+1
end

Set @SCountVar=@SCountVar+1
Set @NumSymbStr2=@NumSymbStr2+1
Set @Cnt2 = @Cnt2+1
END

Set @LenStr=@LEnStr+1
END

end
if @SCountVar=0
SET @Res=0
Else
BEGIN
SET @Res=Convert(Numeric (10,5),@SCountEq)/Convert(Numeric (10,5),@SCountVar)
END

RETURN @Res
END

DECLARE @FIO varchar(250)

Set @FIO = 'Иванов Петр'

SELECT
Спр.Code as [ФизЛицоКод],
Спр.ID as [ФизЛицо],
Спр.DESCR as [ФИО],
dbo.fn_FuzzyCompareString(dbo.fn_FIO(Спр.DESCR),@FIO,3) As [Релевантность]
FROM
SC503 as Спр (nolock)
where
ISMARK = 0
and
ISFOLDER = 2
and
dbo.fn_FuzzyCompareString(dbo.fn_FIO(Спр.DESCR),@FIO,3)>=0.8
GO