This is a post about SYSDATE() and NOW() and CURRENT_TIMESTAMP() functions in MySQL.

Firstly, note is that of these three, only CURRENT_TIMESTAMP() is part of the SQL Standard. NOW() happens to be an alias for CURRENT_TIMESTAMP() in MySQL.

Secondly, note that replication does not work well with non-deterministic functions. And “hey, what time is it?” is non-deterministic. Ask it twice, with a second apart between asking, and both times you get different results (with at least second precision).

You can start to see the problem here….but there’s more…. (more…)

Background Knowledge

Since MySQL v4.1 timestamp and datetime data types are formatted “YYYY-MM-DD HH:MM:SS”. Prior to MySQL v4.1 the timestamp was formatted as YYYYMMDDHHMMSS” and datetime formatted as “YYYY-MM-DD HH:MM:SS”. Refer to MySQL Reference Manual for further details.

The Unix timestamp differs from MySQL. Unix’s timestamp is a integer value of seconds since January 1, 1970. For further explanation of Unix timestamps refer to Wikiepedia or UnixTimestamp.com.

Solutions

In MySQL you can use Unix_Timestamp() function.

Query Example: SELECT …