2/16/2001

>

> what if my hw 3 is not correct?

> should i still base my hw 4 on hw 3?

>

Yes, do your HW #4 based on what you turned in for HW #3.

2/22/2001

>

> 1. according to the lecture notes, when we have a multivalued attribute we

> should enclose them in {braces}, and should be listed with the appropriate

> entity. however, according to the text book, it tells us to create a

> completely NEW relation for the multivalued attribute (see page 220 of

> text). please clarify which one is expected for the homework. or does it

> not matter???

>

Either option is acceptable. Once we cover normalization, you'll see that they are the same thing. For now, you can just use the {braces}.

> 2. the lecture notes list several options for dealing with sub/super - type

> entities - do you prefer us to use a certain method - or can we choose which

> ever one we want??

You can use whatever method you think is best.

> I had a few questions about the HW for IRM. In the first question, I was

> not too sure what to do with composite attributes.

> For example, the address attribute has street, city and zip attached to

> it. While making the database schema, do I just write address in the

> student table, or do I include street and all.

>

For composite attributes, do not put the composite attribute in the schema, put just the simple attributes. So for the address example, you only include street, city, etc. You could indicate that they are from a composite attribute by naming them addr_street, addr_city, etc. but that is optional.

> Also, in the second question, you have given the list of attributes that

> is the minimum required. If we put down this list with the correct keys,

> is this sufficient? Or do we need to write down attributes for every

> entity.

I have only given you the minimum required attributes. Every entity should have at least one attribute, and you can add attributes as you think necessary.