Why do I get this error when trying the next query?

Message: SQL type for this field is not yet supported.

private void getCliente(String cnpj)
{ try
{
stm = c.createStatement();
ResultSet rs = stm.executeQuery("SELECT * FROM CLIENTES WHERE
CNPJ='"+cnpj+"'");
if (rs.next())
{
campoNome.setText(rs.getString("NOME"));
campoCNPJ.setEnabled(false);
}
rs.close();

}
catch(SQLException se)
{
se.printStackTrace();
}
}
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