Datatool DTLifnull not working

Question

Considering the following database:

Name,ID,Gender,Years in Service
,382473856,M,15
Francesca Joestar,461276432,F,10
Chan Ker Mei,463724631,F,5
Hikaru Yagami,154954739,M,10

The first line has the field "Name" empty. The following code does not work. In fact the function:

\DTLifnull{\name}{Mister X}{\name}

always gives the result FALSE. Why?

\documentclass[16pt]{scrartcl}
\usepackage[left=3cm,right=3cm,top=6cm,bottom=5cm]{geometry}

\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{tgschola}
\usepackage{fourier-orns}
\usepackage{graphicx}
\usepackage{wallpaper}

\usepackage{datatool}
\DTLloaddb{names}{namelist.csv}

\begin{document}
\linespread{2}\selectfont
\pagestyle{empty}
\TileWallPaper{\paperwidth}{\paperheight}{old-border}

\DTLforeach{names}{
\name=Name, \ID=ID, \gender=Gender, \yr={Years in Service}}{
{\centering
    {\LARGE\bfseries Certificate of Appreciation}\par
    {\LARGE\decofourleft\quad{\decoone}\quad\decofourright}\par
    \vskip2em
    We thank\par
    {\large\bfseries\MakeUppercase{\DTLifnull{\name}{Mister X}{\name}}}\par
    {\large (ID: \ID)}\par
    for having been with\par
    {\large XYZ Company}\par
    {for \emph{\LARGE\yr} glorious years}\par
    \vskip1em
    We commend \DTLifeq{\gender}{M}{him}{her} on \DTLifeq{\gender}{M}{his}{her} excellent service.\par
    }

    \vfill

    \hfill
    \begin{minipage}{.4\textwidth}
    Managing Director\par
    \vskip1cm
    \rule{8em}{.5pt}
    \vskip-1em
    (MD's Name)\par
    \end{minipage}

    \pagebreak
}
\end{document}

Answer 1

This is documented on page 66 of the user manual of datatool (end of section 5.5).

You can define a test for emptyness:

\newcommand{\myDTLifempty}[3]{%
  \if\relax\detokenize\expandafter{#1}\relax#2\else#3\fi
}

and then say

\DTLforeach{names}{
\name=Name, \ID=ID, \gender=Gender, \yr={Years in Service}}{
{\centering
    {\LARGE\bfseries Certificate of Appreciation}\par
    {\LARGE\decofourleft\quad{\decoone}\quad\decofourright}\par
    \vskip2em
    We thank\par
    {\large\bfseries\MakeUppercase{\myDTLifempty{\name}{Mister X}{\name}}}\par
    {\large (ID: \ID)}\par
    for having been with\par
    {\large XYZ Company}\par
    {for \emph{\LARGE\yr} glorious years}\par
    \vskip1em
    We commend \DTLifeq{\gender}{M}{him}{her} on \DTLifeq{\gender}{M}{his}{her} excellent service.\par
    }
  ...
}