I'm new to the forums, so hope you can all help.

I need to do some pretty basic data work but, despite being good at this stuff once upon a time, I've not had a need to do db work / analysis in this way for a couple of decades so I'm a little rusty on what software is best for this specific use case. I'm looking for something relatively low cost since this is just a piece of analysis I'll be doing for a few hours, once a month.

So, here's the use case.

Each month I receive a list of all of my company's customers (uniquely referenced by their 'account name') and, for each, how much they used our system in that month (number of clicks). So it's basically two columns - the first called 'account name' and the second called 'clicks'.

I'll get one of these files each month. So Nov-14, Dec-14, Jan-15, etc.

The number of rows in the file increases each month as we add new customers to our company. However, we also lose some customers, so some disappear from the report. So, the point is that the list of accounts is not the same each month. And of course, for the accounts that DO appear in multiple months, the number of clicks differs from month to month.

The analysis I'm trying to do is to compare, for a subset of customers (more on that in a minute) the total number of clicks done in a particular month last year to the total number of clicks in the same month this year. i.e. the year-on-year growth in usage of our system by the population as a whole.

The subset of customers should only include customers that had clicks above a certain threshold in BOTH months that I'm comparing - i.e. over 5,000 clicks in Dec-13 and over 5,000 clicks in Dec-14. Doing this means that I filter out the customers that joined during the year (they would have no clicks in Dec-13) and those that left during the year (they would have no clicks in Dec-14). This effectively gives me an 'index' for how customers that have been with us throughout the period have grown their use of the system. Make sense?

So, what I'm looking for is a simple piece of software where I can import the list of customers and clicks each month and it will look up the account name (primary key) and if it already exists, it will add the latest data to that customers row. And if the key doesn't exist it will create a new row for that customer.

I'm sure this is a lot simpler than I'm making it - so please, can you help me out?

Thank you!