Order of cursor walk

I have table Stock which represents products in stock.
When new order came (table orders) I must reserve items in stock for that
order (table reservations).
The way I work is, that I first find all appropriate stock for my order,
walk through it and reserve the quantity until I reach
order quantity:
declare @.stockQ decimal(15,5),@.orderQ decimal(15,5),@.orderID int,@.stockID
int,@.orderIDold int,@.work bit,@.quantity decimal(15,5)
set @.orderIDold=0
declare cCur cursor local for
SELECT o.orderID,s.stockID,o.quantity,s.quantity from orders o LEFT JOIN
stock s
ON o.productID=s.productID
AND (o.quality is null OR o.quality=s.quality)
AND (o.producer is null OR o.producer=s.producer)
open cCur
fetch next from cCur into @.orderID,@.stockID,@.orderQ,@.stockQ
while @.@.fetch_status=0
begin
set @.stockQ=@.stockQ-(SELECT isnull(sum(quantity),0) from reservations
where stockID=@.stockID)
if isnull(@.stockQ,0)>0
begin
if @.orderID<>@.orderIDold
begin
SET @.work=0
SET @.orderIDold=@.orderID
set @.quantity=@.orderQ
end
if @.work=0--(if @.work=1 then all quantity for this order was
already reserved)
begin
if @.stockQ>=@.quantity
begin
INSERT INTO reservations
SELECT @.orderID,@.stockID,@.quantity
set @.work=1
end
else
begin
INSERT INTO reservations
SELECT @.orderID,@.stockID,@.stockQ
set @.quantity=@.quantity-@.stockQ
end
end
end
fetch next from cCur into @.orderID,@.stockID,@.orderQ,@.stockQ
end
close cCur
deallocate ccur
GO
It works.
The problem is, when I have in table orders more products with the same ID
and different other parameters.
With sample data you can see (just copy the script below and run my query)
that reservation that this query create is
ORDERID STOCKID quantity
---
1 1 100
Instead I reserve both orders I reserve only first.
So, I should include somehow the right order of select statement.
The reservation should be:
ORDERID STOCKID quantity
---
1 2 100
2 1 100
How can I solve that? Any idea?
This is simple example I use to explain the situation.The real example has
many parameters, not only quality and producer, and many
different products with different quantity.
So, the real combination shoul reserve the maximum possible orders.
The sample data with tables:
if exists (select * from dbo.sysobjects where id =
object_id(N'[dbo].[stock]') and OBJECTPROPERTY(id, N'IsUserTable') = 1)
drop table [dbo].[stock]
GO
if exists (select * from dbo.sysobjects where id =
object_id(N'[dbo].[orders]') and OBJECTPROPERTY(id, N'IsUserTable') = 1)
drop table [dbo].[orders]
GO
if exists (select * from dbo.sysobjects where id =
object_id(N'[dbo].[reservations]') and OBJECTPROPERTY(id, N'IsUserTable') =
1)
drop table [dbo].[reservations]
GO
CREATE TABLE [dbo].[stock] (
[stockID] [int] NOT NULL ,
[productID] [int] NOT NULL ,
[quality] [char] (1) COLLATE SQL_Slovenian_CP1250_CI_AS NOT NULL ,
[producer] [varchar] (10) COLLATE SQL_Slovenian_CP1250_CI_AS NULL ,
[quantity] [decimal](15, 5) NULL
) ON [PRIMARY]
GO
CREATE TABLE [dbo].[orders] (
[orderID] [int] NOT NULL ,
[productID] [int] NULL ,
[quality] [char] (1) COLLATE SQL_Slovenian_CP1250_CI_AS NULL ,
[producer] [varchar] (10) COLLATE SQL_Slovenian_CP1250_CI_AS NULL ,
[quantity] [decimal](15, 5) NULL
) ON [PRIMARY]
GO
CREATE TABLE [dbo].[reservations] (
[orderID] [int] NOT NULL ,
[stockID] [int] NOT NULL ,
[quantity] [decimal](15, 5) NULL
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[stock] ADD
CONSTRAINT [PK_products] PRIMARY KEY CLUSTERED
(
[stockID]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[orders] ADD
CONSTRAINT [PK_orders] PRIMARY KEY CLUSTERED
(
[orderID]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[reservations] ADD
CONSTRAINT [PK_reservations] PRIMARY KEY CLUSTERED
(
[orderID],
[stockID]
) ON [PRIMARY]
GO
INSERT INTO orders(orderID,productID,producer,quanti
ty) VALUES (1,1,'2',100)
INSERT INTO orders(orderID,productID,quality,quantit
y) VALUES (2,1,'A',100)
INSERT INTO stock(stockID,productID,quality,producer
,quantity) VALUES
(1,1,'A','2',100)
INSERT INTO stock(stockID,productID,quality,producer
,quantity) VALUES
(2,1,'B','2',100)
regards,SCursors don't have a predictable order unless you specify ORDER BY in
the cursor declaration.
You can do this possibly more efficiently without a cursor. Google for
FIFO and stock inventory in this group to find some examples.
David Portas
SQL Server MVP
--|||well, I mean the order of SELECT statement which cursor use.
I don't know how to find the right order. There is a lot of combinations.
I thought, the result of this simple example I posted should give me the
right guidline in real example.
I already look for fifo in google but haven't find the similar example.
Can you help me?
thanks ,S
"David Portas" <REMOVE_BEFORE_REPLYING_dportas@.acm.org> wrote in message
news:1128676869.547922.139950@.g44g2000cwa.googlegroups.com...
> Cursors don't have a predictable order unless you specify ORDER BY in
> the cursor declaration.
> You can do this possibly more efficiently without a cursor. Google for
> FIFO and stock inventory in this group to find some examples.
> --
> David Portas
> SQL Server MVP
> --
>|||Take a look at this thread:
http://groups.google.co.uk/group/mi...b653f3ad3fcaa5e
David Portas
SQL Server MVP
--