Whether you’re selling groceries, financial services, or gym memberships, successful recruitment of new customers is only truly successful if they return to buy from you again. The metric which reflects this is called retention, and the approach we use is customer retention analysis. It’s one of the key metrics that influences revenue. When your customers’ retention is law, you’ll spend all of the income from your business on marketing. At the same time, retention is easy to improve if you can calculate it the right way using SQL and your database. In this post, we’ll guide you step by step on how to make basic customer retention analysis, how to build customer retention over time, new vs. existing customers retention curves, and how to calculate retention analysis in cohorts.