update all phone numbers to 10 characters : I have a table which have phone numbers filed.In this many records of phones numbers. Some are 10 characters ,While some are less than 10 and some  are greater than 10. Now i want to select the records then update all the records to 10 characters. If phone number is less then 10 add leading 0 to make it 10. While if greater than 10 then remover last digits to make 10