stored procedures

Question

i want to retrieve values from database using stored procedure,compare those values to the parameter supplied in the query string...if the value retrieved from the database using stored procedure  equals the parameter supplied in the query string an updation should take place and reflect that changes to my database.......
i have 2 columns named activated and user id in my database,using stored procedure user id should be retrieved and compare that value with parameter supplied in query string and if the comparison is successful an updation of column "activated" should be done......... how the whole thing gets done using stored procedure