Mandatory and Non mandatory in non identifying relationships <p>With reference to the last part of answer given here: <a href="http://stackoverflow.com/questions/762937/whats-the-difference-between-identifying-and-non-identifying-relationships">What&#39;s the difference between identifying and non-identifying relationships?</a></p> <blockquote> <p>A non-identifying relationship can be optional or mandatory, which means the foreign key column allows NULL or disallows NULL, respectively.</p> </blockquote> <p>I am creating a non-identifying relationship in MySQL Workbench and whether I keep foreign key column MANDATORY or NON-MANDATORY, has no effect. Even if it is NON-MANDATORY I can't enter NULL values in it. I have to explicitly choose that particular foreign key as allowing NULL and only then I am able to store NULL values.<br> So I want to ask if this is the correct behaviour or this is a problem with MySQL Workbench or MySQL?</p> <p>Thanks</p>