I want to generate random 6 digit number in mysql but sometime it generate only 5 digit.
UPDATE member SET updates = FLOOR(RAND() * 999999)
If the problem is that you are missing leading zeros, you can left pad with spaces:
UPDATE member SET updates = LPAD(FLOOR(RAND() * 999999.99), 6, '0');
I hope you understand that "random" means "random" and different rows can get the same value.