Conversion from Date ("yyyy/mm/dd") to ("dd/mm/yyyy")

Question

I’m using a field of sorts Date in the archive HTML, to facilitate the selection of the date, but it will be saved to the bank in American format yyyy/mm/dd, I did the following query to transform this data and show in a dd/mm/yyyy , but it didn’t work:

$seleciona= mysqli_query($conexao,"
    SELECT TO_Char(r.Data,'dd/mm/yyyy'),r.CodReuniao Datas
    FROM reuniao r
    group by TO_Char(r.Data,'dd/mm/yyyy')
    order by Datas ASC"
);

Have some syntax error?