Question

I need to add a auto-inc surrogate key to three tables in my data warehouse:

Note: These are not the real table names

JakMaster (JakMasterId, Date) (PK) Note: JakMasterId is varchar(60)

JakToRoad (JakMasterId, Date) (FK)

JakToBig (JakMasterId, Date) (FK)

What steps should I take to add a surrogate key to these three tables so that the new keys reference each other correctly?

Thanks!

Answer 1

I’m assuming you are wanting to replace JakMasterId with an auto-increment field so the other two tables don’t need a varchar(60) field and to improve query times, but that you are keeping JakMasterId as information.

-- set database single-user

-- drop foreign keys

create table NewMaster (ID int identity(1, 1), JakMasterId, Date))
insert NewMaster(JakMasterId, Date) select JakMasterId, Date from JakMaster
drop table JakMaster
sp_rename 'NewMaster', 'JakMaster'

alter table JakToRoad add MasterId int
alter table JakToBig add MasterId int

update JakToRoad set MasterId = JakMaster.ID
from JakToRoad
inner join JakMaster on JakMaster.JakMasterId = JakToRoad.JakMasterId

update JakToBig set MasterId = JakMaster.ID
from JakToBig 
inner join JakMaster on JakMaster.JakMasterId = JakToBig .JakMasterId

alter table JakToRoad drop column JakMasterId
alter table JakToBig drop column JakMasterId


alter table JakToRoad add constraint FK_JTRtoJM foreign key (MasterId) references JakMaster (ID)
alter table JakToBig add constraint FK_JTBtoJM foreign key (MasterId) references JakMaster (ID)

-- reset database to multi-user