dbExpress design question - delphi

Question

Does anybody know (or care to make a suppostion as to) why TSqlDataset has a commandtext property (string) whereas TSqlQuery has a sql property (tstrings)?
Consider the sql statement
select id, name from
table
order by name
If I use a TSqlQuery, then I can change the table name in the query dynamically by accessing sql[1], but if I am using a TSqlDataset (as I have to if I need a bidrectional dataset, the dataset is connected to a provider and thence to a tclientdataset), I have to set the commandtext string literally. Whilst the above example is trivial, it can be a problem when the sql statement is much more involved.
Update:
Judging by the comments and answers so far, it seems that I was misunderstood. I don't care very much for improving the runtime performance of the components (what does one millisecond matter when the query takes one second) but I do care about the programmer (ie me) and the ability to maintain the program. In real life, I have the following query which is stored in a TSqlQuery:
select dockets.id, dockets.opendate, customers.name, statuses.statname,
dockets.totalcost, dockets.whopays, dockets.expected, dockets.urgent,
(dockets.totalcost - dockets.billed) as openbill,
(dockets.totalcost - dockets.paid) as opencost,
location.name as locname, dockets.attention,
statuses.colour, statuses.disporder, statuses.future, dockets.urgcomment
from location, statuses, dockets left join customers
on dockets.customer = customers.id
where dockets.location = location.id
and dockets.status = statuses.id
I haven't counted the number of characters in the string, but I'm sure that there are more than 255, thus precluding storing the query in a simple string. In certain circumstances, I want to filter the amount of data being displayed by adding the line 'and statuses.id = 3' or 'and customers.id = 249'. If the query were stored as TStrings, then I could add to the basic query the dummy line 'and 1 = 1', and then update this line as needed. But the query is one long string and I can't easily access the end of it.
What I am currently doing (in lieu of a better solution) is creating another TSqlDataSet, and setting its commandtext to the default TSqlDataSet's commandtext whilst appending the extra condition.

Answer 1

1) TSQLQuery is rather for compatibility with BDE TQuery. And BDE TQuery has SQL: TStrings property. TSQLDataSet is what supposed to be used for new applications.
2) Although SQL: TStrings is usefull for some tasks, it is also error prone. Often programmers forget to clear SQL property before filling again. Also if your query is a big one, the filling of SQL may lead to performance degradation. Because on each SQL.Add(...) call dbExpress code parses query when ParamCheck is True. That may be solved by using BeginUpdate / EndUpdate or setting ParamCheck to False. But note, setting ParamCheck to False stops automatic parameters creation.
SQLQuery1.SQL.BeginUpdate;
try
SQLQuery1.SQL.Clear;
SQLQuery1.SQL.Add('SELECT * FROM');
SQLQuery1.SQL.Add('Orders');
finally
SQLQuery1.SQL.EndUpdate;
end;
CommandText does not have such issues.
3) You can use Format function for building a dynamic SQL string:
var
sTableName: String;
...
sTableName := 'Orders';
SQLDataSet1.CommandText := Format('select * from %s', [sTableName]);
4) Other data access libraries, like AnyDAC, have macro variables, simplifying dynamic query text building. For example:
ADQuery1.SQL.Text := 'SELECT * FROM &TabName';
ADQuery1.Macros[0].AsRaw := 'Orders';
ADQuery1.Open;

Answer 2

I would have to say that the TSqlQuery uses TStrings (TWideStrings in Delphi 2010) because it is much more flexible.
Suppose your query was:
Select
Item1,
Item2,
Item3,
Item4
FROM MyTable
It's a lot easier to read
You can copy and paste into an external query tool and it stays formatted
It's easy to comment out sections
Select
Item1,
/*
Item2,
Item3,
*/
Item4
FROM MyTable
You can easily add items
Select
Item1,
Item2,
Item2a,
Item2b,
Item3,
Item3a,
Item3b,
Item4
FROM MyTable
Try doing that to a contiguous set of characters that goes on forever in one long line with no line breaks inside an edit window that is always to small for viewing that doesn't allow for wrapped text etc. etc. etc.
Just $0.02.