Delphi EDataBaseError - Operation Not Supported. How can I solve it?

I'm trying to query data from MySQL5 db, but when I use some other features from SQL code, I have the following error returned: [0x0005]: Operation Not Supported.

My SQL code query:

Select 
  s.nome, s.id_sistema, s.st_sis 
from 
  perm_usuar as p 
inner join 
  sistemas as s 
on 
  s.id_sistema = p.id_sistema 
where 
  p.id_usuario = "' + idusuario + '"'

When I don't use those features, it works just as well:

Select 
  sistemas.nome, sistemas.id_sistema, sistemas.st_sis 
from 
  perm_usuar 
inner join 
  sistemas 
on 
  sistemas.id_sistema = perm_usuar.id_sistema 
where 
  perm_usuar.id_usuario = "' + idusuario + '"'

Also, if I try to use WHERE of a joined table, I get the same error... I'm using DBExpress on Delphi XE8, with the following components: SQLConnection, SQLDataSet and SQLQuery.

When I use the code directly on MySQL, it works fine.

Why is it being returned and what's the solution?

Solution

I found the solution! The problem were on SQLQuery1.RecordCount. By what I read, the dbExpress is unidirectional, so the RecordCount bring it resource, however have its limitations (you can see here: http://edn.embarcadero.com/ru/article/28494)

Before (returning error):

 SQL1.SQL.Clear;
 SQL1.SQL.Add(CodigoMYSQL);
 SQL1.Open;
 SQL1.First;
 cont := SQL1.RecordCount; //have limitations
 if cont > 0 then // check
  begin
   for i := 1 to cont do //loop in
    begin
     for ii := 0 to NValue do
      result[ii].Add(SQL1.Fields[ii].AsString);
     SQL1.Next;
    end;
  end;
 SQL1.Close;

** SQL1 = SQLQuery1

After (solved):

 SQL1.SQL.Clear;
 SQL1.SQL.Add(CodigoMYSQL);
 SQL1.Open;
 SQL1.First;
 if not SQL1.IsEmpty then //check
  begin
    ii := 0;
    while not SQL1.Eof do //till the end
    begin
     for ii := 0 to NValue do
      result[ii].Add(SQL1.Fields[ii].AsString);
     SQL1.Next;
     inc(ii);
    end;
  end;
 SQL1.Close;

Now I can use even more complex one SQL codes and functions.