What's the difference in int(11) and int(11) UNSIGNED?

Question

What\'s the difference in int(11) and int(11) UNSIGNED ?

Answer 1

All integer types can have an optional (nonstandard) attribute UNSIGNED. Unsigned type can be used to permit only nonnegative numbers in a column or when you need a larger upper numeric range for the column. For example, if an INT column is UNSIGNED, the size of the column's range is the same but its endpoints shift from -2147483648 and 2147483647 up to 0 and 4294967295.

see here: http://dev.mysql.com/doc/refman/5.0/en/numeric-types.html