Index questions

First of all, is it necessary to create an index on the primary key column of a table (as almost every search I do is on the primary key)?

Secondly, I have one table where I will regularly do a search like this: select * from users where u_name = 'blah' and u_index = 10;

In other words, I will reguarly search for table rows based on those two columns together (The two columns, when combined, will be unique, but each column by itself will not be unique).

Is this how I create an index to speed up the mentioned queries?

CREATE unique INDEX username_index on users (u_name asc, u_index asc);

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 Kirk Bauer -- CmpE, Georgia Tech -- kirk_at_kaybee.org -- Avid Linux User
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