I want to put a vertical line to the table

\usepackage{babel}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{cfr-lm} % instead of the "[cyr]{aeguill}"
\usepackage[table]{xcolor}
\usepackage{ragged2e} % new
\usepackage{booktabs, % new
makecell, % new
tabularx} % new
\renewcommand\theadfont{\small\bfseries}
\renewcommand\theadgape{}
\newcolumntype{L}{>{\RaggedRight}X} % redefined
%---------------------------------------------------------------%
\begin{document}
\begin{table}[htb]
\footnotesize
\setlength\tabcolsep{4pt}
\begin{tabularx}{\linewidth}{@{}
>{\large}c
>{\hsize=0.25\hsize}L
>{\hsize=0.25\hsize}L
>{\hsize=0.50\hsize}L @{}}
\toprule
\thead[l]{RG}
& \thead[l]{Définition}
& \thead[l]{Mapping}
& \thead[l]{Règles de gestion spécifiques} \\
\midrule
1 & Portail Date Traitement Courant
& RBP vTBADMRB \_SUIVI\_APPLI.D \_TRAIT
& CASE WHEN
[RBP Presentation View].[Dimension Référentiel Datamart].[L\_DATMR]
= 'PORTAIL' THEN [RBP Presentation View].[Fait Suivi Application].[D\_TRAIT] END \\
\bottomrule
\end{tabularx}
\caption{Équipe de travail}
\end{table}
\end{document}

booktabsrules– vertical rules will be broken. But anyway, where in your table do you want to have vertical rules? – Bernard May 27 '18 at 15:32booktabswithout vertical rules as it is now is just fine. – moewe May 27 '18 at 15:32\toprule,midruleandbottomrulewith\hline(ii) table specifier change to:\begin{tabularx}{\linewidth}{|>{\large}c| >{\hsize=0.25\hsize}L| >{\hsize=0.25\hsize}L|| >{\hsize=0.50\hsize}L|}– Zarko May 27 '18 at 15:49