Creating Continuous Contract in MySQL

I'm trying to make some Futures Continuous Contract for personal use. I have created some php code which scraping some websites for end of day (EOD) data. This data is stored in my MySQL database. The code is set to run each day at a specific time by cron job. My problem is now to use this data and assemble this into continuous contract. I’m open for reconstruction of they way data is stored if it will make it more efficient. Right now I store data in one table which contains EOD data for all open futures contracts. I then want the row with the highest value in column x in this table to be returned to another table. Them should only be one value at each date, and it shouldn’t be able to jump over a contract or jump back to the previous contract if the value at those in a mystery way turn higher again. I hope you can understand my problem/job.