But basically I feel that this schema is rigid, not particularly well normalized, and would do well to have constraints such as this one applied in a business logic layer rather than at this level ...

Jul. 16, 2010 4:17 AM ET 1 Comment John Petersen's Blog 55.82K Follower s Follow ...

Carrell: Timing constraints seem pretty simple. It’s an SDC file, but it rapidly grows to become a script that includes all the other tools in the flow. There are first-party, second-party and ...

In my system, a picture can be associated with a user or a news article, but not both. Thus, I have a table with 2 foreign keys where exactly one of them is valid. I did this like so:CREATE TABLE ...