Another extension is supported by MySQL for optionally specifying the display width
of an integer value in parentheses following the base keyword for the type (for example, INT(4)).
This optional width specification is used to left-pad the display of values whose width is less
than the width specified for the column, but does not constrain the range of values that can
be stored in the column
, nor the number of digits that will be displayed for values whose width
exceeds that specified for the column. When used in conjunction with the optional extension
attribute ZEROFILL, the default padding of spaces is replaced with zeroes. For example, for a column
declared as INT(5) ZEROFILL, a value of 4 is retrieved as 00004. Note that if you store larger
values than the display width in an integer column, you may experience problems when
MySQL generates temporary tables for some complicated joins, as in these cases MySQL trusts
that the data did fit into the original column width.