Dropping a Unique Key?

How do I drop a Unique key from a table in my database? I know I should Alter table, however there doesn't seems to have an option to drop just the Unique key but not the primary key. Change and modify does seems to do it either.. Jaso

Select partial DATE?

this? In a nutshell, how do I select some DATE type of data just by year and month match? Thanks Jason Lam