Converting PascalCase string to "Friendly Name" in TSQL

Question

I have a table with a column whose values come from an Enumeration. I need to create a TSQL function to convert these values to "Friendly Names" upon retrieval.

Examples:

 'DateOfBirth' --> 'Date Of Birth'
 'PrincipalStreetAddress' --> 'Principal Street Address'

I need a straight TSQL UDF solution. I don't have the option of installing Extended Store Procedures or CLR code.

Answer 1

If you're using SQL Server 2005, you can write a native CLR procedure:

static string ToFriendlyCase(this string PascalString)
{
    return Regex.Replace(PascalString, "(?!^)([A-Z])", " $1");
}

Outputs:

Convert My Crazy Pascal Case Sentence To Friendly Case

If you're not using 2005, then you've gotta either parse it manually or reference the regex object using extended procedures. A good article can be found here:

http://www.codeproject.com/KB/mcpp/xpregex.aspx

Edit: A UDF can't affect the database, so you can't register the regex com object, so that casts that idea out. A stored procedure however, can - so that might be a route.

In order to do a case sensitive comparison, you're going to have to set the collation for the query to be case sensitive, and then use a replace I think... here's an article that might be helpful in pointing you off in the right direction:

http://www.mssqltips.com/tip.asp?tip=1032

Answer 2

/*
 Try this.  It's a first hack - still has problem of adding extra space
 at start if first char is in upper case.
*/
create function udf_FriendlyName(@PascalName varchar(max))
returns varchar(max)
as
begin

    declare @char char(1)
    set @char = 'A'

    -- Loop through the letters A - Z, replace them with a space and the letter
    while ascii(@char) <= ascii('Z')
    begin
     set @PascalName = replace(@PascalName, @char collate Latin1_General_CS_AS, ' ' + @char) 
     set @char = char(ascii(@char) + 1)
    end

    return LTRIM(@PascalName) --remove extra space at the beginning

end

Answer 3

declare @arg varchar(20)
set @arg = 'DateOfBirthOnMonday'

declare @argLen int
set @argLen = len(@arg)

declare @output varchar(40)
set @output = ''

declare @i int
set @i = 1

declare @currentChar varchar(1)
declare @currentCharASCII int

while (1 = 1)
begin
set @currentChar = substring(@arg, @i, 1)
set @currentCharASCII = ascii(@currentChar)

if (@currentCharASCII >= 65 and @currentCharASCII <= 90)
set @output = @output + ' ' 

set @output = @output + @currentChar

set @i = @i+ 1

if (@i > @argLen) break
end

set @output = ltrim(rtrim(@output))
print @output

Change the value of @arg to something, you want to test with.

Also, you might need to change the @output declaration to accommodate string which has same length as the @arg + number of spaces it might need. I have doubled it in my example.

Answer 4

Not the most elegant solution, but it works:

declare @pascalCasedString nvarchar(max) = 'PascalCasedString'
declare @friendlyName nvarchar(max) = ''
declare @currentCode int;
declare @currentChar nvarchar;

while (LEN(@pascalCasedString) > 0)
    begin
     set @currentCode = UNICODE(@pascalCasedString)
     set @currentChar = NCHAR(@currentCode)

     if ((@currentCode >= 65) AND (@currentCode <= 90))
     begin
      set @friendlyName += SPACE(1)
     end
     set @friendlyName +=  @currentChar
     set @pascalCasedString = RIGHT(@pascalCasedString,LEN(@pascalCasedString) - 1)
    end

select @friendlyName