SQL Query Corn Job

I have 2 tables in database with date field, one is used to store messages of members and other one store visitor log. what i want is to create a corn job which will check once a day and delete log & messages which are older then 30 days. Also i have one table which store buddies now some time due to user the buddy and friendship request sent to other twice so it add same member twice as in friend list, so i need a query to check the list for duplicate and delete the duplicate entry. So basically i require a coder to create 3 query to do this job ## Deliverables Database SQL Query