Different types of languages deal with this “value” in diverse ways. You can have a more comprehensive list of what NULL can mean on this website. What I like to think about NULL is along the lines of invalid, as if some sort of garbage is stored there. It doesn’t mean it’s empty, it’s just mean that something is there, and it has no value to you.

Databases deal when storing this type in a similar way, PostgreSQL treats it as “unknown” while MySQL treats it as “no data“.

Both databases recommend using \N to represent NULL values where import or exporting of data is necessary.

When …

MySQL 5.6.17 was recently released (it is the latest MySQL 5.6, is GA), and is available for download here:

For this release, I counted 7 “Functionality Added” and/or “Incompatible Change” fixes:

1. Incompatible Change: The AES_ENCRYPT() and AES_DECRYPT() functions now permit control of the block encryption mode and take an optional initialization vector argument.
2. Incompatible Change: The ERROR_FOR_DIVISION_BY_ZERO, NO_ZERO_DATE, and NO_ZERO_IN_DATE SQL modes now are deprecated and setting the sql_mode value to include any of them generates a warning. In MySQL 5.7, these modes do nothing. Instead, their effects are included in the effects of strict SQL mode (STRICT_ALL_TABLES or …