PHP复选框设置为基于数据库值进行检查

I have a system where people fill in their information and later can go back and edit certain parts, basically the enter personal info and check whether they want to know extra info, these bits of extra infos are checkboxes, 4 of them. the user will select up to any of the 4 and the database has 4 fields set to no, if they select one it changes to yes. I want them to be able to go back and deselect or reselect any of these 4 checkboxes, so what i want s for the checkboxes to be selected if the values is yes and unselected if the value is not.I have a system where people fill in their info