how to display \thesubsection by a letter

Question

I want to have in each frame a title like this : 1 - "section name" : a) "subsection name"

I have done something like that : \thesection \, - \secname \,: \thesubsection ) \subsecname

but it displays 1 - "section name" : 1) "subsection name"

How can I do ?

my code :

%...
\begin{frame}
\frametitle{Table of Contents}
\tableofcontents
\end{frame}

\section{Analyse de l'article}
    \subsection{Principes fondamentales}
    
        \begin{frame}{\thesection \, - \secname \,: • \subsecname}
            blabla
        \end{frame}
        
\section{Création de modèles prédictifs}

    \subsection{Mise en forme des données}
    
        \begin{frame}{\thesection \, - \secname \,: • \subsecname}
        \end{frame}
        

%---------------------------------------------------------

\end{document}

Answer 1

You can use \alph{<counter name>} to show the value of the counter as lowercase letters:

\documentclass{beamer}

\newcommand{\mytitle}{
  \thesection \, - \secname \,:
  \alph{subsection}) \subsecname
}

\begin{document}

\begin{frame}
  \frametitle{Table of Contents}
  \tableofcontents
\end{frame}

\section{Analyse de l'article}
\subsection{Principes fondamentales}

\begin{frame}
  \frametitle{\mytitle}
  blabla
\end{frame}

%\section{Création de modèles prédictifs}

\subsection{Mise en forme des données}

\begin{frame}
  \frametitle{\mytitle}
  blabla
\end{frame}

\end{document}