No. TH is essentially a bolded TD tag. In MSSQL, a table w/o a
clustered index is a "heap", the rows are in random order. A table
with a clustered index, physically stores its rows in the clustered
index and is ordered by the index keys. A non clustered index is based
off the clustered index (if there is one). The reason why indexes are
important is that the data lives on disk. The database doesn't load
the entire table into memory, waiting for you. When you perform a
query, it goes out to disk and fetches a subset of rows, hopefully by
using a index. Otherwise it has to scan the entire table. (Try
scanning a phone book. It's not much fun if it isn't sorted.) If you
want an analogy, an index is more like a memory pointer. I don't think
it's possible to explain indexes in one paragraph. Suggest reading up
on it in Books On Line.
