What is the significance of the number in parentheses after the data type in MySQL table column definitions?

The number in parentheses after the data type in MySQL table column definitions represents the length or size constraint for that particular data type. It specifies the maximum number of characters or digits that can be stored in that column. It is important to define this number accurately to ensure data integrity and optimize storage space.

// Example of defining a column with a length constraint in a MySQL table using PHP
$createTableQuery = "CREATE TABLE users (
                        id INT(11) AUTO_INCREMENT PRIMARY KEY,
                        username VARCHAR(50),
                        email VARCHAR(100)
                    )";