software

I have four columns which relate to hiring new staff -

column A - the name of an employee (this name can appear more than once)
column B - the name of the task they will work on
column C - the start date for the task
column D -- the category of person they are. ie. driver, dispatcher, legall,
accounts etc.

I would like to construct a table that extracts the following information:

How many new people in each month will start in our company. If the name
appears for a task starting in May and again for task starting in August - I
only want them counted as starting in May.

How many different categories of person are hired in each month - basically
splitting teh above info into categories.

Any help appreciated.

Thanks,

Ellebelle