… and what of this all has to do with IBAN numbers.
The modulus is the remainder of a division of two integers*. Suppose you divide 12 by 4, the result is 3. But divide 11 by 4, and the result is 2.75. This could also be expressed by saying that 11/4 is 2 with a remainder of 3. Computing that 3 is the work of the modulo operator, which in T-SQL is represented by the % operator.
Let’s explore how to compute the modulus of large numbers in SQL Server, and how this is useful in the real world.
Talk to SQL Server developers or DBAs about histograms, and they’ll inevitably think of index statistics. However, a task you may encounter some day is to calculate the distribution of numbers in a table. And although there’s no quick built-in function to do this, it’s not as difficult as you may think.
When you’re using Microsoft Outlook, or pretty much any other personal information manager, you can create calendar appointments that are “recurring”, i.e. you can have them repeat at a defined frequency. This, however may not only apply to your project meeting appointments, but also to some database solution. I decided to give it a go at building a table value function that returns a list of dates, based on a given set of parameters.
I stumbled upon a challenge on a blog i follow, to find prime numbers using T-SQL. With a little bit of Wikipedia research, I’ve built a T-SQL version of the “sieve of Eratosthenes“.