MySql: Tinyint (2) vs tinyint(1) - what is the difference?

I knew boolean in mysql as tinyint (1).

Today I see a table with defined an integer like tinyint(2), and also others like int(4), int(6) ...

What does the size means in field of type integer and tinyint ?

The (m) indicates the column display width; applications such as the MySQL client make use of this when showing the query results.

For example:

| v   | a   |  b  |   c |
+-----+-----+-----+-----+
| 1   | 1   |  1  |   1 |
| 10  | 10  | 10  |  10 |
| 100 | 100 | 100 | 100 |

Here a, b and c are using TINYINT(1), TINYINT(2) and TINYINT(3) respectively. As you can see, it pads the values on the left side using the display width.

It's important to note that it does not affect the accepted range of values for that particular type, i.e. TINYINT(1) still accepts [-128 .. 127].

It means display width

Whether you use tinyint(1) or tinyint(2), it does not make any difference.

I always use tinyint(1) and int(11), I used several mysql clients (navicat, sequel pro).

It does not mean anything AT ALL! I ran a test, all above clients or even the command-line client seems to ignore this.

But, display width is most important if you are using ZEROFILL option, for example your table has following 2 columns:

A tinyint(2) zerofill

B tinyint(4) zerofill

both columns has the value of 1, output for column A would be 01 and 0001 for B, as seen in screenshot below :)