TSQL Removing tab and line feed from xml values

Question

I'm trying to select a value from a xml column field with the following query:

SELECT LTRIM(LocalData.value('(/root/questionphrase[@ln="nl"]/xhtml/p)[1]', 'nvarchar(max)'))
FROM Question

The structure of my xml:

<root>
  <questionphrase ln="nl">
    <xhtml>
      <p>
         Data I want to select</p>
    </xhtml>
  </questionphrase>
</root>

I'm getting back the expected values but they all start with 2 whitespaces. After some investigating it turns out there's a tab char(9) and a line feed character char(10) at the beginning of the string. Is there a generic way to strip these characters from the output without manually replacing them? I was hoping LTRIM and RTRIM would do the trick, but no luck so far.

Note: I only want to replace the characters in the beginning and the end of the string

Answer 1

You can create separate trim functions:

Trim Functions:

CREATE FUNCTION dbo.LTrimE(@str VARCHAR(MAX)) RETURNS VARCHAR(MAX)
AS
BEGIN
    DECLARE @trimchars VARCHAR(10)
    SET @trimchars = CHAR(9)+CHAR(10)+CHAR(13)+CHAR(32)
    IF @str LIKE '[' + @trimchars + ']%' SET @str = SUBSTRING(@str, PATINDEX('%[^' + @trimchars + ']%', @str), 8000)
    RETURN @str
END
GO
CREATE FUNCTION dbo.RTrimE(@str VARCHAR(MAX)) RETURNS VARCHAR(MAX)
AS
BEGIN
    DECLARE @trimchars VARCHAR(10)
    SET @trimchars = CHAR(9)+CHAR(10)+CHAR(13)+CHAR(32)
    IF @str LIKE '%[' + @trimchars + ']'
    SET @str = REVERSE(dbo.LTrimX(REVERSE(@str)))
    RETURN @str
END
GO
CREATE FUNCTION dbo.TrimE(@str VARCHAR(MAX)) RETURNS VARCHAR(MAX)
AS
BEGIN
    RETURN dbo.LTrimE(dbo.RTrimE(@str))
END
GO

Your query will then look like

SELECT dbo.TRIME(LocalData.value('(/root/questionphrase[@ln="nl"]/xhtml/p)[1]',
'nvarchar(max)'))
FROM Question

Original Source for Trim functions

Answer 2

You can try to build a CLR function, that takes the string value as a parameter.

Then just do what you want with it in c#, and return the correct trimmed value, something like this:

    [Microsoft.SqlServer.Server.SqlFunction(DataAccess=DataAccessKind.None)]
    [return: SqlFacet(MaxSize = -1)]
    public static SqlString TrimValue([SqlFacet(MaxSize = -1)] SqlString value) {
        if(value.IsNull || value.Value.Length == 0) return value;

        string trimmedValue = value.Trim();
        return new SqlString(trimmedValue);
    }