I have a custom attribute for min\_price I need to update this field using data from the cost field using a formula. (cost+1.50)/.84 

Any ideas on how I can do this? 

I've tried to make since of the EAV database and do it in MySQL directly but it's confusing to say the least. 

<https://stackoverflow.com/questions/24580872/mysql-multiple-select-statements-with-an-update>