Executing Prepared Statements with FireDAC Classes

By default, TFDQuery prepares the query to avoid recompiling the same query over and over.

FDQuery1.SQL.Text := 'SELECT * FROM Inbox WHERE From=:From' 
FDQuery1.ParamByName('From').AsString := '[email protected]';
FDQuery1.Open;

Notes

• If you need to execute a command only once, set ResourceOptions.DirectExecute to true.
• The TFDConnection class is most useful for one-off data manipulation commands, where prepared statements are unnecessary.
• The connection must be active and open while a statement is prepared.