What is the Purpose of the Number in Data Types like `tinyint(2)` and `int(4)` in MySQL?

Understanding the Difference Between Tinyint(2) and Tinyint(1) in MySql

While it is known that a boolean data type in MySql is represented as tinyint(1), you may have encountered a table where integers are defined as tinyint(2), or other variations such as int(4), int(6), and so on. This article aims to clarify the significance of these numbers in the context of integer and tinyint data types.

The number (m) following the type name, such as tinyint(m), indicates the column's display width. This value is primarily used by applications like the MySQL client to determine the formatting and padding of the displayed results.

For instance, consider the following table structure:

| v (tinyint(1)) | a (tinyint(2)) | b (tinyint(3)) | c (tinyint(4)) |

The display width of the values in these columns will be as follows:

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

As you can see, the values are padded with spaces on the left side to match the specified display width.

It is crucial to note that the display width does not affect the range of accepted values for the data type. For example, a tinyint(1) column will still accept values between -128 and 127, regardless of its display width.

In summary, the number following the tinyint or int data type in MySql (m) represents the column's display width, which affects how the values are formatted and padded when displayed in applications. It does not impact the valid range of values for that particular data type.

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