INNER JOIN

UniQuery3.SQL.Add('  Select * from PartAll PA');

UniQuery3.SQL.Add(' inner join Tcategory C on PA.Idcategory=C.idcategory ');

UniQuery3.SQL.Add(' inner join TBrand B on C.IdBrand=B.idBrand ');

 UniQuery3.SQL.Add(' inner join TType T on B.IdBrand=T.NoBrand');

 UniQuery3.SQL.Add('where B.IdBrand=:idT');

 UniQuery3.ParamByName('idT').AsInteger:=Integer(lst3.Items.Objects[lst3.ItemIndex]);