I have a field in my mysql database called 'rank'.

I want to run a simple as possible query or php loop that checks if there's an increment starting from 1 in this field across all rows. Doesn't matter the order of the rows, just as long as there's a row with 'rank' of 1, another of 2, another of 3, etc.

I have some code to run if there's a break in the sequence so Im just looking for help on the most resource friendly way of checking.

There needs to be a row with a rank of 1 also.