Understanding the Limitations of Subqueries: How to Avoid "Subquery Returned More Than 1 Row" Errors in Your Queries.

Selecting Data with Conditional References in SQL Using Subqueries

Using read_csv to Specify Data Types for Groups of Columns in R: A Practical Approach with Regular Expressions and type.convert

Marking Rows in a Data Frame as "TRUE" if Specific Number Inside Group Appears