Reverse only numerical parts of string in sql server

Question

With T-SQL, I'm trying to find the easiest way to reverse numbers in string. so for string like Test123Hello have Test321Hello.

[Before]           [After]
Test123Hello       Test321Hello
Tt143 Hello        Tt341 Hello
12Hll              21Hll
Tt123H3451end      Tt321H1543end

Answer 1

you can use this function

    CREATE  FUNCTION [dbo].[fn_ReverseDigit_MA]
(
    @Str_IN nVARCHAR(max)   
)
RETURNS NVARCHAR(max)
AS
BEGIN   
    DECLARE @lenstr AS INT =LEN(@Str_IN)
    DECLARE @lastdigend AS INT=0


    while (@lastdigend<@lenstr)
    BEGIN

        DECLARE @strPart1 AS NVARCHAR(MAX)=LEFT(@Str_IN,@lastdigend)
        declare @lenstrPart1 AS INT=LEN(@strPart1)
        DECLARE @strPart2 AS NVARCHAR(MAX)=RIGHT(@Str_IN,@lenstr-@lastdigend)

        declare @digidx as int=patindex(N'%[0-9]%'  ,@strPart2)+@lenstrPart1
        IF(@digidx=@lenstrPart1)
        BEGIN
            BREAK;
        END     
        DECLARE @strStartdig AS NVARCHAR(MAX) = RIGHT(@Str_IN,@lenstr-@digidx+1)

        declare @NDidx as int=patindex(N'%[^0-9]%' ,@strStartdig)+@digidx-1
        IF(@NDidx<=@digidx)
        BEGIN
            SET @NDidx=@lenstr+1
        END
        DECLARE @strRet AS NVARCHAR(MAX)=LEFT(@Str_IN,@digidx-1) +REVERSE(SUBSTRING(@Str_IN,@digidx,@NDidx-@digidx)) +RIGHT(@Str_IN,@lenstr-@NDidx+1)
        SET @Str_IN=@strRet
        SET @lastdigend=@NDidx-1        
    END
    return @Str_IN  
END