semi/signal

I was curious what to name a variable holding a string with a date formatted for MySQL. Something like “startDateMysql” seemed silly, so I went digging as to what MySQL’s date format was based on.

The YYYY-MM-DD format used by MySQL is defined by ISO 8601.

The HH:MM:SS format is also defined by ISO 8601, but MySQL never adds the time zone designator, a ‘Z’ indicator for UTC or an offset from UTC. Without the time zone designator, the time is implied to be local time according to the standard, but MySQL returns non-local time without a designator, which is non-conformant.

When combining a date and time, MySQL omits the ‘T’ delimiter, which is allowed and permitted by “mutual agreement.”

Random timestamps are fairly simple to generate and useful when creating test data or fake data for demos. The technique involves converting a MySQL timestamp into unix time, adding or subtracting a certain time range (in seconds), then converting back to a MySQL timestamp.

I’ve used this technique presented on underdog-projects.net before, where a starting timestamp is specified and a random time span is added to the timestamp. However, I wanted to try something slightly different and, in my opinion, a bit more robust. Instead of specifying a starting timestamp, I wanted a pivot timestamp from which a random time span is randomly added or subtracted.

Of course all the variables can be made part of the SELECT statement to make everything more succient.