How to replace an empty date value? I am trying to replace many null date values in a single column using this query:

UPDATE animal SET
  BirthDate = '1900-01-01 06:00:00 AM' 
WHERE BirthDate = '''


MySQL shows this error:


  You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'UPDATE animal SET
    BirthDate = '1900-01-01 06:00:00 AM' 
  WHERE BirthDate = ''' at line 1.


How can this be resolved? I use Toad for MySQL interface editor.
For starters, your GUI shouldn't matter, but it's normally good to use the CLI - i.e. the mysql client - or at least as a backup in case of results you are having problems interpreting.
Second, have you tried IS NULL instead of the = comparison? 
Third, what's wrong with NULL? Normally, you should use the appropriate datatype - why is NULL a problem? If you don't know the date of birth, there's nothing wrong with it. For example, if you want to perform an AVG calculation, you'll have problems. Your population will appear much older than it really is. NULLs however will be ignored in such a calculation, so no anomalous results (the same goes for all such calculations).