Title: Create an index for a TClientDataSet at runtime
Question: When I had to create an index for a in-memory table, I got the
error message 'No active index' when accessing the index e.g. with FindKey().
Answer:
I had originally created the index with the property IndexName
and finally found out that this did not select my index.
Selecting the index by the property IndexFieldNames worked fine,
as the following source shows.
This is also an example how to create a memory table..
with CDS1 Do
begin
Close;
// Define the fields
FieldDefs.Clear;
FieldDefs.Add ('Project', ftInteger, 0, True);
FieldDefs.Add ('Module', ftString, 60, False);
FieldDefs.Add ('FuncName',ftString, 60, False);
FieldDefs.Add ('FuncDate',ftDate, 0, False);
FieldDefs.Add ('FuncCRC', ftString, 2, False);
FieldDefs.Add ('Programmer', ftString, 32, False);
// Define the index
IndexDefs.Clear;
IndexDefs.Add ('IProject', 'Project;Module;FuncName',
[ixPrimary, ixUnique]);
// this seems not to do anything
IndexName := 'IProject';
// this does work
IndexFieldNames := 'Project;Module;FuncName';
// Create the dataset
CreateDataSet;
Open;
end;