CS145 - Introduction to Databases
Spring 2000, Prof. Widom

FAQ: Written Assignment #1

Question: How will the written assignments be graded?

Answer: See the General FAQ.

Question: Problems 3(e) and 4(c) ask for "a different relational schema ... that still captures the same information". Do I need a new E/R diagram as well?

Answer: No. The idea here is to create a relational schema that's different from the one generated from your E/R diagram. For example, what kind of relational schema might you come up with if you created it from scratch, without creating an E/R diagram first?

Question: I have an entity set and/or a relation that has multiple keys. (For example, in relation Student(SS#,name,address), it could be that (name,address) is one key and SS# is another.) What should I do?

Answer: Multiple keys do occur in practice. In an entity set in the E/R model or a relation specification in the relational model there is no way to specify multiple keys: you can only underline one set of attributes as the key. If there are other keys that you would like to mention, make a separate note. When you get around to creating actual relations in an actual DBMS, there is a way to specify more than one key.

Question: Problem 3 asks me to create a schema for a Web site of my choosing. I'm doing essentially the same thing for my PDA. Can I turn in the same solution for both?

Answer: Yes, no problem. Be sure to follow the instructions in each assignment carefully though.