want to change value in record if size is less then 12

i am new for mysql, here is my question i hope you guys will help me to resolve this.

i want a query for update if record is less then 12 Charc and want to make it 12 char with starting 0

i.e i have record " 123456789123 " but if record is "123456789" where 3 char is missin from the starting means ( 000123456789 ) so i want to add 0 or 00 or 000 to make it 12 charc record.

regards and thank in advanced for all.

 

use the lpad function

update tablename
set recordname = lpad(recordname,12,'0')
where "anyfilter"

Code (markup):

reference http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_lpad