Question

I just created one role table and i defined role_id tinyint(1), even though i was able to store 99, 200 max upto 255 as tinyint limit for unsigned. so then what is the meaning of passing this size in data-types?

when read little that, it is about the display width, but when i fetch result on my php page, it displays as they are stored in the table.

Any mentor, can you please guide me to clear it?

Answer 1

from 10.1.1. Numeric Type Overview:

M indicates the maximum display width for integer types. The maximum legal
display width is 255. Display width is unrelated to the range of values a type
can contain [...].

So tinyint(M), or tinyint(1) in your case, means that any value stored in role_id will be chopped to a length of one byte when being displayed by MySQL. Similarly tinyint(3) would case a one digit integer to be padded with two spaces. You can also use tinyint(3) zerofill to pad with 0s instead, but it has the side-effect of making your tinyints unsigned.

However, regardless how you specify your tinyints they will be stored internally as an integer in the range [-128,127] (signed) or [0,255] (unsigned), and so that’s the value PHP will receive when querying your database.

You can use mysql_field_len and substr to limit the display width similarly with PHP.