Deployment errors, "There is already an object named 'PK_***' in the database. Could not create constraint." - sql

Question

When I try to run my app, I get the following errors:
There is already an object named 'PK_***' in the database. Could not create constraint."
That's actually two errors combined for brevity. Note: the asterisks are my own; that is not the actual name of the key.
I've scoured what seems like every post on here, but I can't seem to get any further in finding a solution. The worst part? No one else in the team is experiencing these errors when they run, nor can they determine why I am. We are all using the same environment, VS 2012 Premium RC. I certainly have latest from TFS.
I am wondering if anyone else has come across an issue similar to this where the problems/errors occurred in only one person's environment? I can continue and run the app. It seems to run as expected, but I am the only one getting those errors.

Answer 1

In SQL Server constraints such as primary keys or foreign keys are objects in their own right, even though they are dependent upon the "containing" table.
That means that their names must be unique within the owning schema. So, just as executing DDL along the lines of
create table some_schema.foo
(
id int not null
)
go
create table some_schema.foo
(
id int not null
)
go
will raise an error when the second create table is [attempted to be] executed, executing ddl like this will likewise raise an error:
create table some_schema.foo
(
id int not null ,
description varchar(200) not null ,
constraint PK primary key clustered ( id ) ,
constraint AK01 unique nonclustered ( description ) ,
)
go
create table some_schema.bar
(
id int not null ,
description varchar(200) not null ,
constraint PK primary key clustered ( id ) ,
constraint AK01 unique nonclustered ( description ) ,
)
go
will likewise raise an error as the constraint that you're trying to create have duplicate names. You need to qualify them with the table name, thusly:
create table some_schema.foo
(
id int not null ,
description varchar(200) not null ,
constraint foo_PK primary key clustered ( id ) ,
constraint foo_AK01 unique nonclustered ( description ) ,
)
go
create table some_schema.bar
(
id int not null ,
description varchar(200) not null ,
constraint bar_PK primary key clustered ( id ) ,
constraint bar_AK01 unique nonclustered ( description ) ,
)
go
and you problem will go away.
It does seem to me that dependent objects that don't exist outside the context of an owing object should be namespaced within the owning object's scope, but that's not the way the SQL standard works.
Good luck!