I am having column with id and news field. The "id" field is showing as primary key in database.

I want the "id" field to be primary only i.e i want it to be incremented by 1. Plus, when i delete any record from this table, it should start counting from deleted number. 

Ex:- if i have 20 records. I deleted the record from 10 to 15. As i deleted 5 records, now the total counting is 15 records. Now i want the database to be start from 16 again. But its taking next number i.e record number 21.

Any help would be appreciated. Thank you.