mysql tinyint(1) vs tinyint(2) vs tinyint(3) vs tinyint(4) [duplicate]

Answer 1

TinyINT = -128...+127

(n) is for display purposes.

Answer 2

According to Mysql manual all decimal numeric types supports syntax:

Integer Types (Exact Value)

When using DECIMAL it allows you to specify precision.

With *INT types it's has mainly display function which also specifies how many places should be added when using ZEROFILL.

The byte size remains unaffected (1B for TINYINT).

Answer 3

TinyINT(M) always has a range from -128..+127 signed or 0..255 unsigned. M is the display width.

M indicates the maximum display width for integer types. The maximum display width is 255. Display width is unrelated to the range of values a type can contain, as described in Section 11.2, “Numeric Types”. For floating-point and fixed-point types, M is the total number of digits that can be stored.

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