all i need is in the single sales table,
The plan is count of accounts grouped by first sale date. That is the easy bit.
the hard bit is i need to look at the data month by month and ignore everything that is more recent.
So if we start in February, how many new customers were there, a new customer is one who bought in february or january.
Then i need to show the situation in January, ie in January how many new customers were there, ie whose first purchase was in January or December.
Then repeat for December…..
I then need to do the same thing based on the last sale date.