SQL to determine minimum sequential days of access?

Question

The following User History table contains one record for every day a given user has accessed a website (in a 24 hour UTC period). It has many thousands of r

Answer 1

Doing this with a single SQL query seems overly complicated to me. Let me break this answer down in two parts.

1. What you should have done until now and should start doing now:
   Run a daily cron job that checks for every user wether he has logged in today and then increments a counter if he has or sets it to 0 if he hasn't.
2. What you should do now:
   - Export this table to a server that doesn't run your website and won't be needed for a while. ;)
   - Sort it by user, then date.
   - go through it sequentially, keep a counter...