BIS524 Chapter 1

Reading data from external files
All of the data so far has been in-line; the data was enclosed inside the DATA step by bracketing it between a DATALINES; and; statements. Almost none of the real data you encounter will be read this way. In the vast majority of cases, the data will reside in a file separate from your SAS code.
How do you read raw data from an external file?
There are two things you have to tell SAS:

What is the long filename that the system uses to identify the file? You will define a "nickname" so that you need only refer to the file by this shorter fileref. This is done with the FILENAME statement.
In the Data step, point to the file so the INPUT statement will know where the data is. This is done with the INFILE statement.