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Sum of calculated field

Posted on 2003-03-04
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Last Modified: 2010-04-04
Howto get sum of a calculated field?
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Question by:tscooter82
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16 Comments
 
LVL 12

Expert Comment

by:esoftbg
ID: 8067292
Example: // Fields:  PRICE, QUANTITY, MONEY
         // MONEY := PRICE * QUANTITY


function  GetSumCalcFields: Double;
var
  D:      Double;
begin
  D := 0;
  try
    Query.Last;
    while not Query.BOF do
    begin
      D := D + (Query.FieldByName('PRICE').AsFloat
              * Query.FieldByName('QUANTITY').AsFloat);
      Query.Prior;
    end;
    Query.First;
  finally
    Result := D;
  end;
end;
.......................................................
There is another way by using SQL:
SELECT SUM(PRICE*QUANTITY) AS MONEY FROM TRADE
0
 
LVL 3

Expert Comment

by:ILE
ID: 8067907

that not work with local bases onli with sql bases

so the solution is for local is

function sum:double;
var r:double;
begin
r:=0;
query1.first;
while not query1.eof do
begin
 r:=r+query1.fieldbyname('calcfieldname').asfloat;
 query1.next;
end;
sum:=r;
end;

0
 

Author Comment

by:tscooter82
ID: 8073502
Is it possible to use sql for fields that are not in the table (only in the query fieldseditor)?
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LVL 12

Expert Comment

by:esoftbg
ID: 8075466
Yes it is possible to use SQL for generating fields like MONEY and FOR_PAY that are not in the table:
SELECT SUM(PRICE*QUANTITY) AS MONEY FROM TRADE
or
SELECT PRICE, QUANTITY, PRICE*QUANTITY AS FOR_PAY FROM TRADE
0
 

Author Comment

by:tscooter82
ID: 8081300
I didnt mean that, i meant:
i have a table which contains 2 columns price,quantity. in the querys field editor i made an field that is called taxes.

my question is: is it possible to use sql like? select taxes from query1?????
0
 
LVL 12

Expert Comment

by:esoftbg
ID: 8087614
if you know the tax-rate (may be 16%) example:

procedure Form1.Proc;
var
  S:   string;
  T:   string;
begin
  T := 'SELECT PRICE, QUANTITY, PRICE*QUANTITY*0.16 AS TAX FROM TRADE GROUP BY PRICE, QUANTITY';
  Query1.Close;
  Query1.SQL.Text := T;
  Query1.Prepare;
  Query1.Open;
  S := Query1.FieldByName('TAX').AsString;
  ShowMessage(S);
end;
0
 

Author Comment

by:tscooter82
ID: 8087658
yes but what is TRADE!! isnt it a database? my question is again: is it possible to use sql on a query which doesnt hava a database connected to it, only fields made in the fields editor!!
0
 
LVL 12

Expert Comment

by:esoftbg
ID: 8087670
it is impossible to use sql like: 'select taxes from query1' because query1 is Delphi component wich can read data from real table from real database.
above example is right way to understand how in the Query1 will appear 3 fields after its Open:
1. Query1.FieldByName('PRICE')
2. Query1.FieldByName('QUANTITY')
3. Query1.FieldByName('TAX')
0
 

Author Comment

by:tscooter82
ID: 8087682
yes. but i have 2 querys. i wantto connect query2 to query1 which contains fields

1. Query1.FieldByName('PRICE')
2. Query1.FieldByName('QUANTITY')
3. Query1.FieldByName('TAX')
0
 
LVL 12

Expert Comment

by:esoftbg
ID: 8087687
it is impossible to use sql on a query which is not connected to a database.
TRADE is a table into DATABASE. TRADE contains two fields: PRICE and QUANTITY.
Query1 reads PRICE and QUANTITY and calculate TAX.
That's all
0
 

Author Comment

by:tscooter82
ID: 8087701
yes but i want another query to calculate the taxes of all the records. or is it possible to have 2 sql statements in the sql texteditor at the object inspector??
0
 
LVL 12

Expert Comment

by:esoftbg
ID: 8087705
what is that "connect query2 to query1" ?
you said that you need to 3 fields from table which contains 2 fields.
my example shows how you get 3 fields into Query1.
i think you don't need Query2 at all !
0
 
LVL 12

Expert Comment

by:esoftbg
ID: 8087732
Query1 does all you want for all records in the table. Imagine that below are the results from executing of Query1. They will be:
PRICE      QUANTITY       TAX
    2             5       1.6
    5             4       3.2    
.............................
   40           2.5      16.0  
0
 

Author Comment

by:tscooter82
ID: 8087733
i have a query which calculates the sum price*quantity of all record and puts it into a field total that isnt a "real" table field. then i wanto count the tax for that field "total" and put it into another "not a table" field. is that possible?
0
 
LVL 12

Expert Comment

by:esoftbg
ID: 8087810
let's think about that:
you need a new field only for "total".
it is possible, but i i think it is not good solution,
i will show how it will seems:

PRICE      QUANTITY       TAX    TOTAL TAX
   2             5       1.6          20.8
   5             4       3.2          20.8
...........................................
  40           2.5      16.0          20.8

is that you need ???????
0
 
LVL 12

Accepted Solution

by:
esoftbg earned 50 total points
ID: 8087837
oh, i understand, you need Query2 only for SUM of the fields. Yes this is possible:
procedure Form1.Proc2;
var
 S:   string;
 T:   string;
begin
 T := 'SELECT SUM(PRICE) AS SUM_PRICE, SUM(QUANTITY) AS SUM QUANTITY, SUM(PRICE*QUANTITY*0.16) AS SUM_TAX FROM TRADE';
 Query2.Close;
 Query2.SQL.Text := T;
 Query2.Prepare;
 Query2.Open;
end;
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