Apology for a lengthy post but I needed to post some code to illustrate the problem.

Inspired by the question What is the reason not to use select * ? posted a few minutes ago, I decided to point out some observations of the select * behaviour that I noticed some time ago.

So let's the code speak for itself:

IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[starTest]') AND type in (N'U'))
DROP TABLE [dbo].[starTest]
CREATE TABLE [dbo].[starTest](
    [id] [int] IDENTITY(1,1) NOT NULL,
    [A] [varchar](50) NULL,
    [B] [varchar](50) NULL,
    [C] [varchar](50) NULL
) ON [PRIMARY]

GO

insert into dbo.starTest(a,b,c)
select 'a1','b1','c1'
union all select 'a2','b2','c2'
union all select 'a3','b3','c3'

go
IF  EXISTS (SELECT * FROM sys.views WHERE object_id = OBJECT_ID(N'[dbo].[vStartest]'))
DROP VIEW [dbo].[vStartest]
go
create view dbo.vStartest as
select * from dbo.starTest
go

go
IF  EXISTS (SELECT * FROM sys.views WHERE object_id = OBJECT_ID(N'[dbo].[vExplicittest]'))
DROP VIEW [dbo].[vExplicittest]
go
create view dbo.[vExplicittest] as
select a,b,c from dbo.starTest
go


select a,b,c from dbo.vStartest
select a,b,c from dbo.vExplicitTest

IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[starTest]') AND type in (N'U'))
DROP TABLE [dbo].[starTest]
CREATE TABLE [dbo].[starTest](
    [id] [int] IDENTITY(1,1) NOT NULL,
    [A] [varchar](50) NULL,
    [B] [varchar](50) NULL,
    [D] [varchar](50) NULL,
    [C] [varchar](50) NULL
) ON [PRIMARY]

GO

insert into dbo.starTest(a,b,d,c)
select 'a1','b1','d1','c1'
union all select 'a2','b2','d2','c2'
union all select 'a3','b3','d3','c3'

select a,b,c from dbo.vExplicittest
select a,b,c from dbo.vStartest

If you execute the following query and look at the results of last 2 select statements, the results that you will see will be as follows:

select a,b,c from dbo.vExplicittest
a1  b1	c1
a2  b2	c2
a3  b3	c3

select a,b,c from dbo.vStartest
a1  b1	d1
a2  b2	d2
a3  b3	d3

As you can see in the results of select a,b,c from dbo.vStartest the data of column c has been replaced with the data from colum d.

I believe that is related to the way the views are compiled, my understanding is that the columns are mapped by column indexes (1,2,3,4) as apposed to names.

I though I would post it as a warning for people using select * in their sql and experiencing unexpected behaviour.

Note: If you rebuild the view that uses select * each time after you modify the table it will work as expected