Record insertion between two tables (selecting when to calculate age)
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Following is my sql query for cron in which i am trying to save records from one table to another table i just want one modification which i could not make that in my i_age field the age should get save in the db but if zero is comming from previous table then the age calculation formula doesnot apply and it saves only zero to i_age field kindly let me know how can i do that , 

THANKS,

    INSERT IGNORE into z_census (i_user_id, v_firstname, v_lastname, i_age)
    			SELECT DISTINCT users.id, users.v_first_name, users.v_last_name,FLOOR((TO_DAYS(NOW())- TO_DAYS(FROM_UNIXTIME(users.i_dob))) / 365.25)
    			FROM users