Why Does INT(x) Affect Display Width But Not Storage in MySQL?

Understanding the Significance of INT() Data Type in MySQL

In MySQL, the INT() data type specifies the maximum display width for integers. By default, this width is set to 11 unless the integer is defined as UNSIGNED, in which case the default width becomes 10. However, you may encounter variations in this width in different tutorials and database schemas.

Purpose of Varying INT() Width

The display width specified in INT(x) primarily affects the appearance of integer values when they are displayed or retrieved from the database. It does not have any impact on the actual storage requirements or performance of the database.

The authors of tutorials or database designers may adjust the display width for various reasons:

• Enhancing Readability: Reducing the display width can make it easier to read and compare integer values, especially in cases where space is limited. For example, an INT(4) field may be used to represent user IDs or sequential numbers, making it convenient to identify individual records.
• Controlling Output Format: By specifying the display width, you can control the formatting of integer values when they are displayed. For instance, an INT(10) field can ensure that values are always displayed with 10 zeros, which may be useful for currency or transaction ID fields.
• Enforcing Constraints: The display width can also be used to enforce constraints on the range of values that can be stored in a field. For example, an INT(2) field would only allow values between -99 and 99, which could be useful for storing boolean flags or small counting values.

Display Width vs. Storage Space

It's important to note that the display width specified in INT(x) does not affect the actual storage space required for the integer values in the database. Integers are always stored as 32-bit values (4 bytes) regardless of their display width.

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