Sort Descending on a Calc.Field

[Henry Olive 5]

Good Day,

How can i sort (descending)  a table on a calculated field ?

Thank You

 

[Lajos Juhász 238]

Calculate the value in sql.

[programmerdelphi2k 235]

you can try using "FDLocalSQL" as your hub:

 

example:

• MyDS_FDMemTableX =  my real data (or any other dataset)
  • in this dataset create a "new field" as "InternalCalc" ... of course, needs to be a field with size and type as your necessity!!!
  • add the event "OnCalcFields" with your expression for create the logic necessary
• now, you'll need 1 FDConnection, 1 FDLocalSQL and 1 FDQuery
  • 1 FDConnection using SQLite, with ":memory" database...   open it!
  • 1 FDLocalSQL to accomodate your dataset desired... 
    • in this case, this dataset will be "MyDS_FDMemTableX"
  • 1 FDQuery will be used to create your SQL select... pointing to your "MyDS_FDMemTableX"
• now, open your FDConnection, FDLocalSQL, and your FDQuery to see the result

for more details see the HELP: Delphi Help -> Example and Samples -> FireDAC.TFDLocalSQL InMemDB Sample

 

procedure TForm1.FDMemTable1CalcFields(DataSet: TDataSet);
begin
  FDMemTable1FullNameInternalCalc.AsString := FDMemTable1LastName.AsString+' '+FDMemTable1FirstName.AsString;
end;
 

MyDS_FDMemTableX:

•     FDMemTable1: TFDMemTable;
•     FDMemTable1FirstName: TStringField;
•     FDMemTable1LastName: TStringField;
•     FDMemTable1FullName: TStringField;
   

FDQuery =    select * from FDMemTable1  order by FullNameInternalCalc

 

 

Edited April 27, 2023 by programmerdelphi2k