Question

i have an application in which a user can lock a certain commodity and once he locks it,he has to pick it up in 2 hours. If he doesnt pick it up in 2 hours then that item is unlocked and user loses 1 locking chance. the user has 3 locking chances initially and if he loses all 3 in 2 months time then he is banned for 2 months. now i have prepared a schema for this but i feel its not optimum. the schema looks like this

user table
--locking_chances_left              //initially 3
--first_chance_miss_date            //date on which the user loses its first locking chance
--second_chance_miss_date           //date on which the user loses its second locking chance
--banned                            // boolean field to indicate whether the user is banned

locked_items table
--item_no
--user_id
--locking_time

banned_users table
--user_id
--ban_date                          //date on which the user is banned i.e lost the last chance

now i have a event which is scheduled to run every minute to see if any item in locked_items table has been locked for more than 2 hours and if it finds any then it removes it from this table which unlocks the item and then decreases locking_chances_left by 1 from the users table. now i have to keep track of whether a user loses all his chances in a period of 2 months to ban him. so i have kept first_chance_miss_date to keep the date when his chances decrease from 3 to 2 and second_chance_miss_date to keep the date when his chances decrease from 2 to 1. i have an after update trigger on users table that checks when the value of locking_chances_left is changed and it updates the first_chance_miss_date and second_chance_miss_date accordingly. is there some better way without using these 2 fields for miss dates and just using one field.
thanks for bearing this

Answer 1

I’d probably do this with a “user_missed_date” table with user_id and missed_date as fields you can then

select user_id, count(*) as misses from user_missed_date where date>[last two months] group by user_id

Or use that as the basis for a subquery.

You would probably want indexes on both user_id, missed_date and missed_date,user_id