mysql - INT(some value) - MYSQL 中的一些值的目的是什么？

Question

我试过写 TINYINT(1)、TINYINT(2) 和 desc 表之后；语句 MYSQL 显示它们是不同的，但是当我尝试将值放入这些字段时，实际大小是相同的 - 从 -127 到 128 或者如果它是 UNSIGNED 到 256。那么使用这个的技巧是什么，我们可以只写 TINYINT 吗？提前致谢。

Answer 1

http://dev.mysql.com/doc/refman/5.5/en/numeric-type-attributes.html

MySQL supports an extension for optionally specifying the display width of integer data types in parentheses following the base keyword for the type. For example, INT(4) specifies an INT with a display width of four digits. This optional display width may be used by applications to display integer values having a width less than the width specified for the column by left-padding them with spaces. (That is, this width is present in the metadata returned with result sets. Whether it is used or not is up to the application.)