Dynamics 365 Business Central: การใช้งาน FlowFields และ FlowFilters ใน AL Programming

        field(50000; "Total Sales"; Decimal)
        {
            FieldClass = FlowField;
            CalcFormula = Sum("Sales Line"."Amount" where("Sell-to Customer No." = field("No.")));
            Editable = false;
        }

        field(50001; "Order Count"; Integer)
        {
            FieldClass = FlowField;
            CalcFormula = Count("Sales Header" where("Sell-to Customer No." = field("No."), "Document Type" = CONST(Order)));
            Caption = 'Order Count';
            Editable = false;
        }

        field(50002; "Average Order Amount"; Decimal)
        {
            FieldClass = FlowField;
            CalcFormula = Average("Sales Line"."Amount" where("Sell-to Customer No." = field("No.")));
            Caption = 'Average Order Amount';
            Editable = false;
        }

        field(50003; "Minimum Sale Amount"; Decimal)
        {
            FieldClass = FlowField;
            CalcFormula = Min("Sales Line"."Amount" where("Sell-to Customer No." = field("No.")));
            Caption = 'Minimum Sale Amount';
            Editable = false;
        }

        field(50004; "Maximum Sale Amount"; Decimal)
        {
            FieldClass = FlowField;
            CalcFormula = Max("Sales Line"."Amount" where("Sell-to Customer No." = field("No.")));
            Caption = 'Maximum Sale Amount';
            Editable = false;
        }

        field(50005; "Has Orders"; Boolean)
        {
            FieldClass = FlowField;
            CalcFormula = Exist("Sales Header" where("Sell-to Customer No." = field("No."), "Document Type" = CONST(Order)));
            Caption = 'Has Orders';
            Editable = false;
        }

        field(50007; "Contact Email"; Text[100])
        {
            FieldClass = FlowField;
            CalcFormula = Lookup(Contact."E-Mail" where("No." = field("Primary Contact No.")));
            Caption = 'Contact Email';
            Editable = false;
        }

CustomerRec.CalcFields("Total Sales");

    var
        CustomerRec: Record Customer;
    begin
        CustomerRec.SetRange("No.", 'CUST001');
        if CustomerRec.FindFirst() then begin
            CustomerRec.CalcFields("Total Sales");
            Message('Total Sales for %1 is %2', CustomerRec."Name", CustomerRec."Total Sales");
        end;
    end;

        field(50001; "Date Filter"; Date)
        {
            FieldClass = FlowFilter;
        }

        field(50000; "Total Sales"; Decimal)
        {
            FieldClass = FlowField;
            CalcFormula = Sum("Sales Line"."Amount" where("Sell-to Customer No." = field("No."),
                                                                "Requested Delivery Date" = field("Date Filter")));
            Editable = false;
        }

 var
        CustomerRec: Record Customer;
        StartDate: Date;
        EndDate: Date;
    begin
        StartDate := DMY2Date(1, 1, 2024);
        EndDate := DMY2Date(31, 12, 2024);

        CustomerRec.SetRange("No.", 'CUST001');
        CustomerRec.SetRange("Date Filter", StartDate, EndDate);

        if CustomerRec.FindFirst() then begin
            CustomerRec.CalcFields("Total Sales");
            Message('Total Sales for %1 from %2 to %3 is %4',
                    CustomerRec."Name", StartDate, EndDate, CustomerRec."Total Sales");
        end;
    end;

procedure GetTotalSales(CustomerNo: Code[20]; StartDate: Date; EndDate: Date): Decimal
var
    CustomerRec: Record Customer;
begin
    CustomerRec.SetRange("No.", CustomerNo);
    CustomerRec.SetRange("Date Filter", StartDate, EndDate);

    if CustomerRec.FindFirst() then begin
        CustomerRec.CalcFields("Total Sales");
        exit(CustomerRec."Total Sales");
    end else
        exit(0);
end;

    var
        TotalSales: Decimal;
    begin
        TotalSales := GetTotalSales('CUST001', DMY2Date(1, 1, 2023), DMY2Date(31, 12, 2023));
        Message('Total Sales is %1', TotalSales);
    end;