I'm looking at the MySQL docs here and trying to sort out the distinction between FOREIGN KEYs and CONSTRAINTs. I thought an FK was a constraint, but the docs seem to talk about them like they're separate things.
The syntax for creating an FK is (in part)...
[CONSTRAINT [symbol]] FOREIGN KEY
[index_name] (index_col_name, ...)
REFERENCES tbl_name (index_col_name,...)
So the "CONSTRAINT" clause is optional. Why would you include it or not include it? If you leave it out does MySQL create a foreign key but not a constraint? Or is it more like a "CONSTRAINT" is nothing more than a name for you FK, so if you don't specify it you get an anonymous FK?
Any clarification would be greatly appreciated.