When should I use UNSIGNED and SIGNED INT in MySQL?

Question

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         


        

Answer 1

I don't not agree with vipin cp.

The true is that first bit is used for represent the sign. But 1 is for negative and 0 is for positive values. More over negative values are coded in different way (two's complement). Example with TINYINT:

The sign bit
|
1000 0000b = -128d  
...  
1111 1101b = -3d  
1111 1110b = -2d  
1111 1111b = -1d  

0000 0000b = 0d  
0000 0001b = 1d  
0000 0010b = 2d  
...  
0111 1111b = 127d