What type of variables must be included in the DATA step columns when using hash objects?

When using hash objects in a DATA step, it is essential to include both key and data components. This is because hash objects are designed to store and manage data in key-value pairs. The key component serves as a unique identifier for accessing the corresponding data component, while the data component holds the information associated with that key.

In practical terms, when you define a hash object, you must specify the key variables that uniquely identify each entry. Then, you also define the data variables that will be associated with these keys. Without both components, the hash object would not have the necessary structure to retrieve or manage data effectively. Therefore, including both the key and data components in the DATA step columns is critical for the proper functionality of hash objects.

Understanding this concept is crucial for efficiently utilizing hash tables in SAS programming, especially in scenarios where fast lookups and dynamic data storage are required.