jpomfret7 (3/5/2014)

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SQLKnowItAll (3/4/2014)

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jpomfret7 (7/13/2011)

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Peter Maloof (7/5/2011)

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David:

I have to disagree that a phone book is an unclustered index.

Unless I'm mistaken, the white pages contain data physically sorted by

last name, first name and address. Once you access the entry

you're looking for, you have all the data; there's no bookmark to follow.

Maybe I'm misunderstanding something, but that sounds like a clustered index to me.

Thanks,

Peter

Peter,

I think the information we are looking for is the hat size rather than the phone number. Once we use the index to get the phone number we then have to use the phone number to get the information. He mentioned the physical houses are not in order which is why it wouldn't be clustered.

Jess

I know this is old, but I am using this piece to help me demonstrate indexes to a group. I'm sorry, but this is still incorrect. The phone book (table) has ITs data organized by last name. That is how the data was being searched; i.e. the White Pages are an example of Clustered index. If we knew the address and not the last name, we could use the street index in the back of the white pages to go to the main part and find the phone number. THAT would be a non-clustered index. I am only posting this because many people come to the stairways to learn, and I want to make sure they understand correctly.

I just want to confirm what is wrong, my understanding (and it could be wrong) is that the phonebook is a clustered index. However, the information that we need to retrieve is the hat size for the girls which is not in the phonebook (clustered index) hence the 'lookup', or phone call to the girls houses to get the hat size.

I'm not sure this is a great example of a nonclustered index, in my head this feels like it would be a join to another table to get the information, but since the data we need is not on the page of the clustered index some kind of lookup is required.

Is this how you see it or are you proposing that in this situation to get last name, phone number and hat size we use a clustered index?

The white pages best represents the concept of a nonclustered index.