calculating Rows in Table

[Perlsau]

Zitat von danten:

Hi friends, I need help with counting rows in database table.
The result should appear in the Edit.

for example:
Col1 = AsString
ROW1 = 345,50
ROW2 = 28,90
row3 = 13,60
row
.
.
row
rowx = 1,08

Code:

TForm1.Button1Click procedure (Sender: TObject);
boiling
  i: integer
  y: double;
begin
    for i: = -1 to Table1.DataSet.RecordCount -1
begin
   y: = Calculate (Table1.Rows);
end;
    Edit1.Text: = FloatToStr(y);
end;

Sorry, I can't see your problem. Or better said: I can see you have a lot of problems with understanding Delphi.

I think you have put a table component on your form which represents the contents of the table in your database. I don't know which table component has got a property named dataset ... What is the name of your database components?

To count means to find out how much rows a table has. You already know the property RecordCount, it reprsents the count of rows.

When you try to make a loop through all records in a table, never use RecordCount, because it only shows you the count of the already fetched records. Better you ask for "End of file":

Delphi-Quellcode:

Dataset.First;

WHILE NOT Dataset.Eof DO
BEGIN
     {do something}

     Dataset.Next;
END;

But I think you don't want to count rows. You want to calculate a sum or compute average. For the last posibility you first have to calculate the sum of the fields and store it in a local variable. After ending the loop you divide the sum with the count of records as divisor:

Delphi-Quellcode:

PROCEDURE MakeAverage;
VAR
   MyAverage,
   MySum      : Currency;
   MyCount    : Integer;

BEGIN
     MyCount   := 0;
     MySum     := 0;

     Dataset.First;

     WHILE NOT Dataset.Eof DO
     BEGIN
          INC(MyCount);
          MySum := MySum + Dataset.FieldByName('SumField').AsCurrency;
          Dataset.Next;
     END;

     MyAverage := MySum / MyCount;
END;