This chapter explores approaches for working with data sets that are larger. Database management systems implementing Structured Query Language (SQL) provide a ubiquitous architecture for storing and querying data that is relational in nature. While the death of SQL has been presaged many times, it continues to provide an effective solution for medium data. The chapter helps the readers learn how to write SQL queries. What is actually happening is that dplyr translates our pipeline into SQL. We can see the translation by passing the pipeline through the show_query() function using our previously created query. The chapter focuses on MySQL, but most aspects are similar in PostgreSQL or SQLite. Every SQL SELECT query must contain SELECT and FROM. The analyst may specify columns to be retrieved.