Question

in MySQL if we create a field dataType of INT and does not specify any length/values then it automatically became int(11) and if we set the attribute UNSIGNED or UNSIGNED ZEROFILL then it turns into int(10)

Where does this length(1) goes?

Answer 1

int value can be -2147483648 these are 11 digits so the default display size is 11

unsigned int does not allow negative numbers so by default it need only display size 10

As the documentation below shows, the number of bits required to store SIGNED INT and UNSIGNED INT is the same, the range of storable numbers is merely shifted:

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.

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