CHECK ((user_id IS NULL AND article_id IS NOT NULL) OR (user_id IS NOT NULL AND article_id IS NULL)) );</pre>Each user or article may have many pictures, but they must have 1 or more featured pictures ...

I've got an interesting constraint I'm trying to add to our database. I can do with with triggers, but am curious if there is a more elegant way to do this in T-SQL (SQL2005, FWIW) We have two related ...

SCL provides a set of functions that enable you to work with integrity constraints (IC). Integrity constraints are a Version 7 feature of SAS software for preserving the consistency and correctness of ...

We describe a new sequential sampling method for constrained multi-way tables, with foundations in linear programming and sequential normal sampling. The method builds on techniques from other ...