Mega Code Archive
Random numbers for Cris .B
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Title: Random numbers for Cris .B
Question: I want to select for example 20 entries at random,from the database,it must give me a different set of numbers every time.
( The application i am creating is a question & Answer Database, the Instructor needs to select for instance 20 Question from the database at random.)
Please Help me
Answer:
I want to select for example 20 entries at random,from the database,it must give me a different set of numbers every time.
( The application i am creating is a question & Answer Database, the Instructor needs to select for instance 20 Question from the database at random.)
Please Help me
ok so u want 20 diferent entrys each time right
i assuming that u use the Ids of the Question records in the Database
Build a array of those records like this
Form1 = Class(TForm)
Public
GetNextNumObject : Array of integer ;
Lastget : Integer ;
// Call at forms create or forms show ;
Procedure Init ;
Function GetQueryInString : String ;
Procedure GetNext20 ;
end;
Procedure TForm1.GetNext20 ;
begin
SomeQuery.Close ;
// This wil look like 'Select * from question where id in (7,2,16,76,4,3,enz)' ;
SomeQuery.sql.text := Format('Select * from question where id in
(%s)' ,GetQueryInString]) ;
SomeQuery.open ;
end;
Procedure TForm1.Init ;
var
I,Temp,Random1,Random2 : Integer ;
begin
i := 0 ;
SomeQuery.sql.text := 'Select ID from question';
SomeQuery.open ;
// if u now record count init the arraya here
// SetLength(GetNextNumObject.ANumberArray,SomeQuery.recordCount) ;
// if not use Setlength everytime
While not SomeQuery.eof do
begin
inc(i);
SetLength(GetNextNumObject.ANumberArray,i);
GetNextNumObject[i-1] := SomeQuery.Fields[0].asinteger ;
SomeQuery.NEXT;
end;
Randomize ;
// Shuffel the data
For i := 0 to 10000 do
begin
Random1 := Random(High(GetNextNumObject)) ;
Random2 := Random(High(GetNextNumObject))
Temp := GetNextNumObject[Random1] ;
GetNextNumObject[Random1] := GetNextNumObject[Random2] ;
GetNextNumObject[Random2] := Temp ;
end;
end;
Function TForm1.GetQueryInString : String ;
var
i : Integer ;
begin
// do we stil have 20 left ? if no do init again
If LastGet + 20 High(GetNextNumObject) then
begin
Init ;
LastGet := 0 ;
end;
for i := lastget to lastget + 20 do
begin
Result := Result ',' + IntToStr(GetNextNumObject[i]);
end;
If result '' then
Result[1] := ' ' ;
Trim(Result);
Inc(LastGet,20);
end;
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