% This file is embedded in datatool-user.pdf version 3.2 2025-03-14
% Example 111 Loading and Saving Data (Be Careful of Category Codes)
% Label: "ex:loadcustomers"
% arara: pdflatex
% arara: pdfcrop
\documentclass[12pt]{article}
\pagestyle{empty}
\begin{filecontents}[noheader,overwrite]{customers.csv}
Id,Organisation,Surname,Forename,Email,Age
1,,Parrot,Polly,pp@example.com,42
2,University of Somewhere,Canary,Mabel,mc@example.com
3,University of Somewhere,Zebra,Zoë,zz@example.com,21
4,Zinnia Florestry,Arara,José,ja@example.com,42
5,,Duck,Dickie,dd@example.com,
6,Newt Fellowship,Axolotl,Lizzie,la@example.com
7,Avian Emporium,Canary,Fred,fc@example.com,19
8,Newt Fellowship,,Molgina,m@example.com
9,,Mander,Sally
10,Élite Emporium,Fant,Eli,ef@example.com,101
\end{filecontents}

\usepackage{datatool}
\DTLsetup{default-name=customers}
\DTLread{customers} 
\begin{document}
\DTLaction[key=Email,value=fc@example.com]{select row}
Row: \number\dtlrownum.
% Save as DBTEX v3.0:
\DTLwrite[format=dbtex-3,overwrite=allow]{customers-v3} 

% Read this new file back:
\DTLread[format=dbtex,name=customers-v3]{customers-v3}
\DTLaction[
 name=customers-v3,
 key=Email,value=fc@example.com
]{select row}
Row: \number\dtlrownum.


% Save original as DBTEX v2.0:
\DTLwrite[format=dbtex-2,overwrite=allow]{customers-v2} 

% `customers' database needs to be deleted as DBTEX v2.0 has the name hard-coded:
\DTLaction{delete}
% Read this new file back:
\DTLread[format=dbtex]{customers-v2}
% Row will no longer be found as DBTEX v2.0 changes category code of `@':
\DTLaction[key=Email,value=fc@example.com]{select row}
Row: \number\dtlrownum. 
\end{document}