Unique Constraint with multiple null columns I have two tables

PC(Id,EmpName Not NULL, PCName NULL, HostName NULL,.... PhysicalLocation NULL, PCType Not NULL)
PCNetwork(Id, EmpName Not NULL, PCName NULL, HostName NULL,IPAddr,....,PhysicalLocation NULL, PCType Not NULL)

Id is a surrogate key, EmpName and PCType are not null fields and the rest can be null. 
I created Unique Constraint on PC with these columns and FK on PCNetwork. If there is a null in one of the column of a record then the constraint works perfect but if more than one column has null the constraint is not working. This is a follow up question of this post

Edit:- My unique constraint and foreign key constriant is not working 

alter table PC add constraint UK_PC_EMPName_PCName_PCType
unique (EMPName, PCName, HostName, PhysicalLocation, PCType);

alter table PCNetwork add constraint FK_PC_PCNetwork
foreign key (EMPName, PCName, HostName, PhysicalLocation, PCType)
references PC (EMPName, PCName, HostName, PhysicalLocation, PCType);
You can create a unique filtered index. Here is a simpler example, since I don't know what your goal is. We have a baseball team and some players have been assigned numbers; some haven't chosen yet.

CREATE TABLE dbo.PlayerUniforms
(
  PlayerID INT PRIMARY KEY,  -- FOREIGN KEY etc.
  UniformNumber TINYINT NULL -- CHECK (COALESCE(UniformNumber,0) &lt; 100)
);

CREATE UNIQUE INDEX x ON dbo.PlayerUniforms(UniformNumber)
  WHERE UniformNumber IS NOT NULL;


Now you can enter multiple NULLs in the UniformNumber column like ANSI meant it to be, and still enforce uniqueness among the non-NULL values.