关于SAS输入文件（AFILE）列描述获取及BFILE数据集字段完整性的技术咨询

How to Retrieve Column Descriptions for the AFILE Input #

Since AFILE is referenced via a JCL DDNAME, here are practical ways to get its column layout:

• Dig into the associated JCL and program code: First, look at the JCL that executes this SAS job. The DD statement for AFILE will tell you the physical dataset it points to. If it's a sequential flat file, the column structure is almost certainly defined in a COBOL copybook, PL/I record layout, or a documentation comment linked to the job that created the file. If AFILE maps to a SAS library (via a LIBNAME statement in SAS or a JCL DDNAME matching the libref), skip to the next point.
• Run PROC CONTENTS in SAS: If AFILE.BFILE is a SAS dataset (i.e., AFILE is a SAS library), execute this simple step to get full column details:

  PROC CONTENTS DATA=AFILE.BFILE;
  RUN;
  

  This will output variable names, data types, lengths, formats, labels, and other metadata directly in your SAS log or output window. If AFILE is a sequential file, you'll need to first read it into a SAS dataset using an INFILE statement with the correct input specifications, then run PROC CONTENTS on that dataset.
• Check internal metadata tools: Many organizations use data catalogs or SAS Metadata Server to track dataset schemas. Search for the dataset name or DDNAME AFILE in these tools—you might find pre-documented column descriptions there.
• Reach out to the job owner or data steward: Sometimes the quickest path is to ask the person who maintains the job or manages the data. They'll likely have the original layout documentation or can point you to where it's stored.

Does the Sorted BFILE Dataset Keep All Columns from AFILE? #

Yes, it will retain every single column from the input AFILE.BFILE dataset.

The PROC SORT procedure in SAS only reorders rows based on the BY variable(s) you specify—in this case, COMPANY—and does not remove any columns unless you explicitly include a KEEP or DROP statement in the step. Since your code doesn't have either, the output BFILE will be an exact copy of the input in terms of columns, just sorted by COMPANY in ascending order (the default; add DESCENDING before COMPANY if you need reverse order).

内容的提问来源于stack exchange，提问作者MCN