Sankar Reddy (7/14/2010)
[font="Courier New"]Going thru the comments, it seems NOT everyone is aware that NOT NULL clause is necessary when altering the column. It’s a simple fact but not everyone knows about that. I am still surprised over ¾ of the people got this incorrectly. I hope at-least few people will know more about NULL bitmap because of this QoD........[/font]
Count me as one who hadn't realized that an ALTER column statement defaults to making it nullable. While the behind-the-scenes, performance related explanation is appreciated, the primary lesson is to include NOT NULL in the ALTER statement unless you really want to change the column to nullable.
One more thought: Isn't it a shame that when we're doing real-world changes we don't get neatly wrapped multiple-choice questions?