The goal when reading an external data file is to create a SAS data set or data view that SAS can process to produce meaningful reports and analyses.This book presents examples of reading external data files and instream data that you can adapt to read your own data.This chapter presents the concepts of reading these data sources with SAS.
Collectively, unprocessed data stored in an external data file or included as part of the job stream are termed raw data.DATA steps read raw data and create SAS data sets and views from the raw data. With the features of the INFILE and INPUT SAS language statements, you describe to SAS the structure of your raw data.You can also specify attributes of an external data file in the FILENAME statement.
As considered in this book, external files contain unprocessed data not stored in a SAS data set.These files can transfer information between software applications and the structures of these files can vary. External files are managed by your operating system, not by SAS. Depending on your operating system, you may refer to your external files as flat files, text files, sequential files,DAT files, or ASCII files.
There is an endless variety of ways in which to store raw data. For example, an external file from a clinical study could contain one data line for one patient for one set of lab tests.Another way of representing the same information is to write a series of data lines for one patient: the first data line contains the patient identifiers and is followed by several data lines, each data line containing the patient's results from a lab test. A third way to create this clinical study file is to place information for multiple patients in each data line.A patient identifier is followed by the lab test results.The information for the next patient continues on the same data line.