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delphi 3

Posted on 2013-06-22
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Last Modified: 2013-07-09
I have two implement below logic,

case function of
1 : Showmessage ('1');
2: Showmessage('2');
3: showmessage('3');

function in above statement shall return 1 or 2 or 3 querying a table on below conditions:

The table has two columns eg A and B, which contain either 0 or 1 values.
First condition shall be querying the table where column B has all 0 values. For this condition the function shall return 1.
Second condition:  Column B has all 1 values and column A has 0 values. For this condition the function shall return 2.
Third condition: Column B has all 1 values and Column A has 1 values, for this condition the function shall returen 3.

Need help with code snippet !
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Question by:AbhiJeet
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5 Comments
 
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Accepted Solution

by:
jimyX earned 500 total points
ID: 39268314
Here is a query that detects your three conditions and returns either 1, 2 or 3, and in case of other order it returns negative:
function CaseResultZeroOne():integer;
begin
  with AdoQry do
    begin
      Close;
      Sql.Clear;
      Sql.Add('select (case Sum(b) when 0 then 1 else');
      Sql.Add('case when (Sum(b) = Count(b)) and (Sum(a) = 0) then 2 else');
      Sql.Add('case when (Sum(a) = Count(a)) and (Sum(b) = Count(b)) then 3 else -2 end end end) AS CaseResult');
      Sql.Add('from DBTable;');
      Open;
      if IsEmpty then
        Result := -1
      else
        Result := FieldByName('CaseResult').AsInteger;
      Close;
    end;
end;

...

case CaseResultZeroOne() of
  1 : Showmessage ('1');
  2: Showmessage('2');
  3: showmessage('3');
end;

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Assuming your table name is "DBTable".
What happens if your conditions are not met?
For instance, if column A is not all ones but column B is all ones?
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LVL 37

Expert Comment

by:Geert Gruwez
ID: 39268625
this is an abstract sample of a problem
as jimyX pointed out, the else condition is missing
or the equation of your abstract problem is not complete
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Author Comment

by:AbhiJeet
ID: 39269039
any other nice and simple work around?
0
 
LVL 24

Expert Comment

by:jimyX
ID: 39269189
It involves DB and records, no other work around.
The only way to do that is to read the records from the database so that's the best that it could be.

Probably you can explain, what did you expect the solution to look like.
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LVL 37

Expert Comment

by:Geert Gruwez
ID: 39269907
from a quote: "nulls are evil"
from the text of your question: either 0 or 1 values

what do you understand as 0 values
> the column has all values as zero (or 0)
> the column has all nulls (or 0 values)

your question contains ambiguities and because of that it's unclear what you want
> you'll have to explain in more detail what you want
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