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Customer registration
Customer cohorts


Let's start with customer acquisition. We'll begin by counting how many new registrations occurred in a given period. By observing how the registration count changes over time, we'll be able to assess whether our promotional campaigns have worked or not.

We'll discuss the following reports:

  • The number of registrations in the given period.
  • The number of registrations in the current period of time (current week, current month, etc.).
  • The number of registrations over time, tallying registrations in each month or in each week.

To count the number of registrations in 2016, we can use the following query:

SELECT COUNT(CustomerID) AS RegistrationCount2016
FROM Customers
WHERE RegistrationDate >= '20160101'
  AND RegistrationDate <  '20170101';

The query is quite simple. Just remember proper time filtering: use the 'yyyymmdd' format (year, month, day) when you write the dates.


How many customers registered in the first six months of 2017? Name the column RegistrationCount.

Stuck? Here's a hint!

To get the first six months of 2017, use the following WHERE clause:

WHERE RegistrationDate >= '20170101'
  AND RegistrationDate <  '20170701';