Format Conversion for MySQL DATE Data Type

When working with MySQL, storing dates in the DATE data type may result in unexpected values like "0000-00-00". This format can be perplexing for visualization and data handling. To address this issue, it's crucial to understand how MySQL represents dates and how to convert them into desired formats.

Internal Representation of MySQL DATE

Internally, MySQL stores dates as a packed three-byte integer, following the formula:

DD MM × 32 YYYY × 16 × 32

For example, the date "2023-03-08" would be stored as "08 03 × 32 2023 × 16 × 32 = 7630668".

Converting to Human-Readable Format for Display

While the internal representation is optimized for storage, for display purposes, it's desirable to convert the date into a human-readable format like "08-03-2023". This conversion can be achieved using the DATE_FORMAT() function.

DATE_FORMAT(datecolumn, '%d-%m-%Y')

For instance, to display the datecolumn as "08-03-2023", the following query can be used:

SELECT DATE_FORMAT(datecolumn, '%d-%m-%Y') AS datecolumn, ...

Cautions for Programming Environments

It's important to note that when accessing dates from a programming environment, it's unwise to convert them to a string format for storage. Instead, it's preferable to retain the raw date value and use the formatting capabilities provided by the programming environment for display purposes.