How to make proper foreign keys in EM? And how to create tables using SQL statem

Hi!

I wonder how to make right foreign keys in Enterprise Manager. I use diagram but in this case I get 'rigid' keys, so I can't delete records. But I want it to set NULL on removing records.

And is it possible to create tables by writing SQl statements in EM? I tried but the new table didn't appear :(.Use Query Analyzer and you will know what are you doing (GUI does not show what it does).sql