Re: => Trigger to split Trailer Loads

From: Rhonda Fischer (anonymous_at_discussions.microsoft.com)
Date: 04/14/04 

Date: Wed, 14 Apr 2004 02:56:06 -0700

Hello Hugo,

Thank you very much for your assistance, it was most helpful. It is a big problem and I'm trying to break it down.
I've started a solution that partially works, however have not as yet given consideration to deleting split orders.
I am using a Trigger and a cursor with a while loop, however the recursive behaviour of the cursor is causing me
some problems, unless it's the algorithm I've used.

I can successfully copy an order from tblOrders to tblSplitOrders, duplicating order details and splitting the load into
multiples of 26 and a final order with the remaining loads. However if there are any more than one table insert I
have incorrect orders copied over.

'******************************************************************************
WORKING EXAMPLE:
'******************************************************************************

INSERT INTO tblOrders (DeliveryID, CollectionID, TempID, OrderDate, NumOfLoads)
VALUES ( 8, 8, 3, '2004-04-13', 106)

'******************************************************************************
My Trace Statements in the Trigger
Load values of first record into local variables
Enter Cursor
Enters LineSplit >0
Split load by multiples of 26 - loop and insert here

(1 row(s) affected)

Split load by multiples of 26 - loop and insert here

(1 row(s) affected)

Split load by multiples of 26 - loop and insert here

(1 row(s) affected)

Split load by multiples of 26 - loop and insert here

(1 row(s) affected)

Insert Loads Remainder

(1 row(s) affected)

Loop to next record in the cursor
Close the Cursor

(1 row(s) affected)
'**************************************************************************************
Data in tblSplitOrders

ID DeliveryID CollectionID TempID OrderDate NumOfLoads
111 8 8 3 13/04/2004 26
112 8 8 3 13/04/2004 26
113 8 8 3 13/04/2004 26
114 8 8 3 13/04/2004 26
115 8 8 3 13/04/2004 2
'***************************************************************************************
And finally the Trigger:

CREATE TRIGGER trgLoadExceedTrlCapacity ON [tblOrders]
FOR INSERT
AS
        /* The purpose of this trigger is to ensure that no entries have in excess of 26 pallet loads */
             /* The Supermarket may order more than 26 loads of produce but the Trailer can only manage 26 loads */
             /* so extra lines are inserted into the new table tblSplitOrders with a maximum of 26 loads */

        Declare @intDeliveryID int, @intCollectionID int, @intTempID int, @dteOrderDate datetime,
                @intNumOfLoads int, @intLineSplit int, @intLoadsRemainder int, @intMaxLoads int, @LoadExcessCursor Cursor

        Set @intMaxLoads = 26

        Set @LoadExcessCursor = Cursor For
                Select DeliveryID, CollectionID, TempID, OrderDate, NumOfLoads,
                        cast(round(NumOfLoads/@intMaxLoads, 0) as int) as LineSplit,
                        NumOfLoads - (cast(round(NumOfLoads/@intMaxLoads, 0) as int) * @intMaxLoads) as LoadsRemainder
                From tblOrders

        Open @LoadExcessCursor

        /*Load values of first record into local variables */
        print 'Load values of first record into local variables'
        Fetch Next From @LoadExcessCursor
        Into @intDeliveryID, @intCollectionID, @intTempID, @dteOrderDate, @intNumOfLoads, @intLineSplit, @intLoadsRemainder

        While (@@FETCH_STATUS = 0)
                begin
                print 'Enter Cursor'
                if @intLineSplit = 0
                        begin
                        print 'Enters LineSplit = 0'
                         /* NumOfLoads between 0-26 insert without splitting order lines*/
                        INSERT INTO tblSplitOrders (DeliveryID, CollectionID, TempID, OrderDate, NumOfLoads)
                        VALUES ( @intDeliveryID, @intCollectionID, @intTempID, @dteOrderDate, @intNumOfLoads)
                        end
                else
                if @intLineSplit > 0
                        begin
                        print 'Enters LineSplit >0'
                        /* NumOfLoads greater than 26 - Split Loads to have a maximum of 26 Loads per record */
                        /* loop to Insert split loads */
                        While @intLineSplit >= 1
                                begin
                                print 'Split load by multiples of 26 - loop and insert here'
                                INSERT INTO tblSplitOrders (DeliveryID, CollectionID, TempID, OrderDate, NumOfLoads)
                                VALUES ( @intDeliveryID, @intCollectionID, @intTempID, @dteOrderDate, @intMaxLoads)
                                Set @intLineSplit = @intLineSplit - 1
                                end
                        /* insert last entry with NumOfLoads equal to LoadsRemainder */
                        print 'Insert Loads Remainder'
                        INSERT INTO tblSplitOrders (DeliveryID, CollectionID, TempID, OrderDate, NumOfLoads)
                        VALUES ( @intDeliveryID, @intCollectionID, @intTempID, @dteOrderDate, @intLoadsRemainder)
                        end
                print 'Loop to next record in the cursor'
                Fetch Next From @LoadExcessCursor
                Into @intDeliveryID, @intCollectionID, @intTempID, @dteOrderDate, @intNumOfLoads, @intLineSplit, @intLoadsRemainder
                end

        print 'Close the Cursor'
        Close @LoadExcessCursor
        Deallocate @LoadExcessCursor

'***************************************************************************************
NOT WORKING EXAMPLE - THREE INSERTS INTO tblOrders
'***************************************************************************************
I then delete all data from the two tables and start again. Just to keep it a bit simpler I have not included any loads
greater than 26 to be split.

INSERT INTO tblOrders (DeliveryID, CollectionID, TempID, OrderDate, NumOfLoads)
VALUES ( 8, 8, 3, '2004-04-13', 2)
INSERT INTO tblOrders (DeliveryID, CollectionID, TempID, OrderDate, NumOfLoads)
VALUES ( 9, 9, 3, '2004-04-13', 5)
INSERT INTO tblOrders (DeliveryID, CollectionID, TempID, OrderDate, NumOfLoads)
VALUES ( 10, 9, 3, '2004-04-13', 9)

'**************************************************************************************
Again my trace statements in the trigger

Load values of first record into local variables
Enter Cursor
Enters LineSplit = 0

(1 row(s) affected)

Loop to next record in the cursor
Close the Cursor

(1 row(s) affected)

Load values of first record into local variables
Enter Cursor
Enters LineSplit = 0

(1 row(s) affected)

Loop to next record in the cursor
Enter Cursor
Enters LineSplit = 0

(1 row(s) affected)

Loop to next record in the cursor
Close the Cursor

(1 row(s) affected)

Load values of first record into local variables
Enter Cursor
Enters LineSplit = 0

(1 row(s) affected)

Loop to next record in the cursor
Enter Cursor
Enters LineSplit = 0

(1 row(s) affected)

Loop to next record in the cursor
Enter Cursor
Enters LineSplit = 0

(1 row(s) affected)

Loop to next record in the cursor
Close the Cursor

(1 row(s) affected)
'***********************************************************************************
And the output in my tblSplitOrders table

ID DeliveryID CollectionID TempID OrderDate NumOfLoads
116 8 8 3 13/04/2004 2
117 8 8 3 13/04/2004 2
118 9 9 3 13/04/2004 5
119 8 8 3 13/04/2004 2
120 9 9 3 13/04/2004 5
121 10 9 3 13/04/2004 9
'*************************************************************************************

I'm not sure why it doesn't work, I expected to copy over three entries of loads 2, 5 and 9. I see the path that the code
has taken but can't understand why it exits the while loop and closes the cursor for some entries and not others.

Are you able to offer me some advice? I've been working hard on this problem and reading lots and your help would
be very much appreciated.

Thank you kindly
Rhonda

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