Multiple Same indexes same table

I was looking at Northwind and noticed that some of the tables have the same
index, but different names on the same table.
For example, on the Orders table you have the following script:
****************************************
************************************
************
CREATE TABLE [dbo].[Orders] (
[OrderID] [int] IDENTITY (1, 1) NOT NULL ,
[CustomerID] [nchar] (5) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
[EmployeeID] [int] NULL ,
[OrderDate] [datetime] NULL ,
[RequiredDate] [datetime] NULL ,
[ShippedDate] [datetime] NULL ,
[ShipVia] [int] NULL ,
[Freight] [money] NULL ,
[ShipName] [nvarchar] (40) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
[ShipAddress] [nvarchar] (60) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
[ShipCity] [nvarchar] (15) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
[ShipRegion] [nvarchar] (15) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
[ShipPostalCode] [nvarchar] (10) COLLATE SQL_Latin1_General_CP1_CI_AS NULL
,
[ShipCountry] [nvarchar] (15) COLLATE SQL_Latin1_General_CP1_CI_AS NULL
) ON [PRIMARY]
GO
CREATE INDEX [CustomerID] ON [dbo].[Orders]([CustomerID]) ON [PRIMARY]
GO
CREATE INDEX [CustomersOrders] ON [dbo].[Orders]([CustomerID]) ON
[PRIMARY]
GO
CREATE INDEX [EmployeeID] ON [dbo].[Orders]([EmployeeID]) ON [PRIMARY]
GO
CREATE INDEX [EmployeesOrders] ON [dbo].[Orders]([EmployeeID]) ON
[PRIMARY]
GO
CREATE INDEX [OrderDate] ON [dbo].[Orders]([OrderDate]) ON [PRIMARY]
GO
CREATE INDEX [ShippedDate] ON [dbo].[Orders]([ShippedDate]) ON [PRIMARY]
GO
CREATE INDEX [ShippersOrders] ON [dbo].[Orders]([ShipVia]) ON [PRIMARY]
GO
CREATE INDEX [ShipPostalCode] ON [dbo].[Orders]([ShipPostalCode]) ON
[PRIMARY]
GO
****************************************
************************************
**
CustomerID and CustomerOrders are the same as are EmployeeID and
EmployeesOrders.
Why would you have this?
This would seem to create more overhead for the system.
Just curious.
Thanks,
Tom>I was looking at Northwind and noticed that some of the tables have the same index, but di
fferent
>names on the same table.
<snip>
> Why would you have this?
Because you don't know what you are doing. ;-)
Honestly, there was some type of confusion in the build scripts for the Nort
hwind database. You
don't create two same type of indexes on the same column.
Tibor Karaszi, SQL Server MVP
http://www.karaszi.com/sqlserver/default.asp
http://www.solidqualitylearning.com/
Blog: http://solidqualitylearning.com/blogs/tibor/
"tshad" <tscheiderich@.ftsolutions.com> wrote in message
news:eSmBW3BpFHA.3304@.tk2msftngp13.phx.gbl...
>I was looking at Northwind and noticed that some of the tables have the sam
e index, but different
>names on the same table.
> For example, on the Orders table you have the following script:
> ****************************************
**********************************
**************
> CREATE TABLE [dbo].[Orders] (
> [OrderID] [int] IDENTITY (1, 1) NOT NULL ,
> [CustomerID] [nchar] (5) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
> [EmployeeID] [int] NULL ,
> [OrderDate] [datetime] NULL ,
> [RequiredDate] [datetime] NULL ,
> [ShippedDate] [datetime] NULL ,
> [ShipVia] [int] NULL ,
> [Freight] [money] NULL ,
> [ShipName] [nvarchar] (40) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
> [ShipAddress] [nvarchar] (60) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
> [ShipCity] [nvarchar] (15) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
> [ShipRegion] [nvarchar] (15) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
> [ShipPostalCode] [nvarchar] (10) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
> [ShipCountry] [nvarchar] (15) COLLATE SQL_Latin1_General_CP1_CI_AS NULL
> ) ON [PRIMARY]
> GO
> CREATE INDEX [CustomerID] ON [dbo].[Orders]([CustomerID]) ON [PRIMARY]
> GO
> CREATE INDEX [CustomersOrders] ON [dbo].[Orders]([CustomerID]) ON [PRIMARY]
> GO
> CREATE INDEX [EmployeeID] ON [dbo].[Orders]([EmployeeID]) ON [PRIMARY]
> GO
> CREATE INDEX [EmployeesOrders] ON [dbo].[Orders]([EmployeeID]) ON [PRIMARY]
> GO
> CREATE INDEX [OrderDate] ON [dbo].[Orders]([OrderDate]) ON [PRIMARY]
> GO
> CREATE INDEX [ShippedDate] ON [dbo].[Orders]([ShippedDate]) ON [PRIMARY]
> GO
> CREATE INDEX [ShippersOrders] ON [dbo].[Orders]([ShipVia]) ON [PRIMARY]
> GO
> CREATE INDEX [ShipPostalCode] ON [dbo].[Orders]([ShipPostalCode]) ON [PRIMARY]
> GO
> ****************************************
**********************************
****
> CustomerID and CustomerOrders are the same as are EmployeeID and Employees
Orders.
> Why would you have this?
> This would seem to create more overhead for the system.
> Just curious.
> Thanks,
> Tom
>|||"Tibor Karaszi" <tibor_please.no.email_karaszi@.hotmail.nomail.com> wrote in
message news:%23q$RciCpFHA.496@.TK2MSFTNGP10.phx.gbl...
same index, but different
> <snip>
> Because you don't know what you are doing. ;-)
> Honestly, there was some type of confusion in the build scripts for the
Northwind database. You
> don't create two same type of indexes on the same column.
I guess I do know what I am doing, since I asked the question :).
I figured there was something wrong, but I wanted to make sure I wasn't
missing something.
Thanks,
Tom
>
> --
> Tibor Karaszi, SQL Server MVP
> http://www.karaszi.com/sqlserver/default.asp
> http://www.solidqualitylearning.com/
> Blog: http://solidqualitylearning.com/blogs/tibor/
>
> "tshad" <tscheiderich@.ftsolutions.com> wrote in message
> news:eSmBW3BpFHA.3304@.tk2msftngp13.phx.gbl...
same index, but different
****************************************
************************************
************
,
NULL ,
[PRIMARY]
[PRIMARY]
[PRIMARY]
[PRIMARY]
****************************************
************************************
**
EmployeesOrders.
>