Calculating days between last login and current date

Question

Upon logging into their accounts, each user has their login date and time stored to the database. What I was looking to do however is figure out the amount of days (or preferably convert into months if greater than a month) so that if a user views their profile they can see how active the band are. Also, this could benefit me in terms of keeping active profiles top of the agenda for content on the site so that it doesn't become stale from inactive users content filling up main page content.

I'm using ColdFusion so i'd be looking for a way to find for example how many days ago #lastLogin# was from #now()#. So say if the date of the last login was 23/04/2013 and todays date is 29/04/2013 it would read "Last Active, 1 day ago." However if the last login was 23/03/2013, it would read "Last Active, 1 month ago".

Anybody know how to do this? Thanks.

P.S I currently have no code from testing this as I have no idea where to start in terms of achieving this.

Answer 1

Use DateDiff

<cfset days = dateDiff("d", LoginDateVariable, now()) />

It's as simple as that.

Answer 2

P.S I currently have no code from testing this as I have no idea where to start in terms of achieving this.

This doesn't answer your direct question but to help you know where to get started, I would strongly suggest reviewing the built in ColdFusion functions and tags that are available to you.

• Tags
  • Tags by function
• Functions
  • Functions by category

Also, Google searches usually land you at the docs, just add "coldfusion" to your search string. Searching google for coldfusion date functions yields very helpful answers, the first of which are a list of all ColdFusion date functions.

Answer 3

Dale's answer is spot on. But I would also suggest returning it as a variable with your query. Let the SQL server do the work. It's very efficient for those types of calculations. Not that CF can't do them well, too. But it's probably more appropriate for SQL to do that lifting. Especially if you're already returning the lastLogin date.

It would be similar to the CF solution:

SELECT ...., lastLogin, DATEDIFF(d, lastLogin, GETDATE()) AS LastLoginDays 
FROM ....
WHERE ....

That would give you the number of days. You'd have to decide how you wanted to define a month if you wanted to break it out by month/day. That would get a bit more complex. You could write a SQL function that could be run on both dates and give you an accurate count of days/months/years since last login.

One other thing to keep in mind: Where are the dates being generated? When you insert loginDate into the database, are you doing a now() in CF before you insert it or are you doing a getDate() in SQL when you insert it? Again, I would let the database do your date logic, but you'd want to compare the two dates from the same source. For instance, if your loginDate was a database getDate() then you may not want to compare that to a CF now(). One goes by the datetime of the SQL server and the other goes by the datetime of the CF server. They could be different.