best way to add column not null

Hi.

I've read up on this, and have something that works, but I was wondering if
there is anything I'm overlooking with this.

Situation is:

I have a bunch of tables.. I need to modify table2 as part of an upgrade of a
database schema.

I am using T-SQL scripts to do the trick which I'm writing myself.

I need to add a new varchar(8) column that is not null to the primary key.
I have a default I would like to use for the initial ddl modification.
I want to get rid of the default after the modification is complete, but leave
the column not null for future operations.
..

(Some if the code I'm using I took from one of Erlands posts.. hope I'm not
abusing it).
Here is the code I'm using now.. it basically adds the column 'institution_id'
as not null along with a default.
Then I jump through a couple of hoops trying to get rid of the default.
Finally I setup the primary key again.

I can only feel I'm supposed to be maybe using a constraint column with a name
to do this easier/more properly.

set @dynamicsql = ' alter table institution_xref add institution_id
varchar(60) not null default ''' + @default_institution_id + ''' '
EXEC (@dynamicsql)
set @dynamicsql = ' alter table institution_xref alter column
institution_id varchar(60) not null '
EXEC (@dynamicsql)
select @institution_iddefault = object_name(cdefault) from syscolumns
where id = object_id('institution_xref') and name = 'institution_id'
exec(' alter table institution_xref drop constraint ' +
@institution_iddefault)
set @dynamicsql = ' alter table institution_xref drop constraint
institution_xref_pk '
EXEC (@dynamicsql)
set @dynamicsql = ' alter table institution_xref with nocheck add
constraint institution_xref_pk primary key clustered (originalcode,
institution_id) '
EXEC (@dynamicsql)

thanks
Jeff
Jeff Kish

Re: best way to add column not null

Jeff Kish (jeff.kish@mro.com) writes:
> I need to add a new varchar(8) column that is not null to the primary key.

Ouch! That can be paintful, at least if there are foreign keys
referencing the table.

> abusing it).
> Here is the code I'm using now.. it basically adds the column
> 'institution_id'
> as not null along with a default.
> Then I jump through a couple of hoops trying to get rid of the default.
> Finally I setup the primary key again.
>
> I can only feel I'm supposed to be maybe using a constraint column with
> a name to do this easier/more properly.

Yes, if you name the constraint it's a little easier:

> set @dynamicsql = ' alter table institution_xref add institution_id
> varchar(60) not null default ''' + @default_institution_id + ''' '

....not null CONSTRAINT my_temp_default DEFAULT ''' ...

> EXEC (@dynamicsql)

ALTER TABLE ... DROP CONSTRAINT my_temp_default




--
Erland Sommarskog, SQL Server MVP, esquel@sommarskog.se

Books Online for SQL Server 2005 at
http://www.microsoft.com/technet/prodtechnol/sql/2005/downlo ads/books.mspx
Books Online for SQL Server 2000 at
http://www.microsoft.com/sql/prodinfo/previousversions/books .mspx

Re: best way to add column not null

On Tue, 5 Jun 2007 22:28:21 +0000 (UTC), Erland Sommarskog
wrote:

>Jeff Kish (jeff.kish@mro.com) writes:
>> I need to add a new varchar(8) column that is not null to the primary key.
>
>Ouch! That can be paintful, at least if there are foreign keys
>referencing the table.
>
>> abusing it).
>> Here is the code I'm using now.. it basically adds the column
>> 'institution_id'
>> as not null along with a default.
>> Then I jump through a couple of hoops trying to get rid of the default.
>> Finally I setup the primary key again.
>>
>> I can only feel I'm supposed to be maybe using a constraint column with
>> a name to do this easier/more properly.
>
>Yes, if you name the constraint it's a little easier:
>
>> set @dynamicsql = ' alter table institution_xref add institution_id
>> varchar(60) not null default ''' + @default_institution_id + ''' '
>
>...not null CONSTRAINT my_temp_default DEFAULT ''' ...
>
>> EXEC (@dynamicsql)
>
> ALTER TABLE ... DROP CONSTRAINT my_temp_default
thanks. much!
Jeff Kish