If you only want there to be one department per employee, you can constrain that relationship and the database enforces it. When an additional department is at

If you only want there to be one department per employee, you can constrain that relationship and the database enforces it. When an additional department is attempted to be added for an employee, it won't be allowed. If you have a list of Films, their title, release date and director, and you don't want additional columns to be allowed to be added, you can set that constraint as well. Let's say now you find out that one film has two directors (a change in relationship cardinality). If you have not constrained it, the default is to allow that to happen. You have schema. The default, though, is to let the data tell you what it is rather than the other way around. > Kayia.org The syntax is properly specified, but the semantics is not. Also, I keep getting lots of JavaScript errors when I try to use your website. There's also a lot of missing information. My apologies; fixes are coming. We didn't plan to submit this to Apply HN -- the opportunity just jumped and so did we. We should have waited and fixed those things and then submitted. Again, apologies, changes are coming.