Question

I have a DATETIME field in a table where I set up as ‘0’ on the insert.
The value ends up being equal to ‘0000-00-00 00:00:00’
When I use:

SELECT ...
 WHERE DATE+INTERVAL 5 MONTH < NOW()

I don’t get these rows. Does that have anything to do with 1970?

Answer 1

The date column is probably null, not 0000-00-00. To verify this try:

WHERE coalesce(DATE,'1900-01-01') + INTERVAL 5 MONTH < NOW()

A comparison with null is neither true nor false, but “unknown”. Since the where clause demands that the condition is true (and not false or unknown) rows with a null date are filtered out of the result set.