It's been inserting the current date and time, 1970, or all zero's depending on what I've tried. The current code inserts the current date and time.
UPDATE:
Sorry it just occurred to me that you may need some additional info. To duplicate the issue.
Type an event name, pick a start date, and check the "All Day" checkbox.
Scroll down and check the "Online Checkin" checkbox
Click Submit.
This should trigger the insert on line 196 to insert a record with NULL values for the checkin_open_date and checkin_close_date columns. The issue is that it inserts a value instead of NULL even when you leave the date and time fields on the form blank.
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