How can I write a column of dates onto a csv file using a format like mm

Currently, I write out dates as a number, i.e. excel date onto a csv file using dlmwrite. That works fine because it is a numeric value. However, how can I take each of excel numbder dates and replace them with year-mm-dd in one cell?

Even something like yearmmdd would work too if someone can tell me how to do that. It has to be mm and dd though for single digit months and days.

Any help please? thanks