Issue
When should I use UNSIGNED and SIGNED INT in MySQL ?
What is better to use or this is just personal prefernce ?
Because I’ve seen it used like this;
id INT(10) UNSIGNED NOT NULL AUTO_INCREMENT
and
id INT(11) NOT NULL AUTO_INCREMENT
Solution
UNSIGNED only stores positive numbers (or zero). On the other hand, signed can store negative numbers (i.e., may have a negative sign).
Here’s a table of the ranges of values each INTEGER type can store:
Source: http://dev.mysql.com/doc/refman/5.6/en/integer-types.html
UNSIGNED ranges from 0 to n, while signed ranges from about -n/2 to n/2.
In this case, you have an AUTO_INCREMENT ID column, so you would not have negatives. Thus, use UNSIGNED. If you do not use UNSIGNED for the AUTO_INCREMENT column, your maximum possible value will be half as high (and the negative half of the value range would go unused).
Answered By – Wiseguy
Answer Checked By – Marie Seifert (BugsFixing Admin)