Q:

MySQL insert date if no field exists

Is there a way in MySQL to get insert date/time for rows if there was no insert_date field.  I have a database which I configured to store insert_date but can I populate the field before that change ( month ago ).  Is that even possible? 
Pull that insert date/time from log or something else? 

A:

Nope.  If that date wasn't stored before, it's impossible to find out when a row was inserted.  The best you can do is just pick a date, or maybe make a rough estimate if you have information to base that on (for instance, the create date of a customer might be related to the date of their first invoice)..
By the way, you can add timestamp columns and specify the clause DEFAULT CURRENT_TIMESTAMP to set a timestamp as soon as you insert the row.  That way, you don't need a trigger to update the row.  
You can even add a clause ON UPDATE CURRENT_TIMESTAMP so the column (or a different column) is updated automatically too.  
See Timestamp initialization for more information about this subject. 
This doesn't change the fact, though, that you cannot get those values for rows that already exist.