Compilation Phase (1)

Understanding DATA Step Processing

Compilation Phase

In this lesson, you work with a DATA step that reads raw data from an external file (which is referenced by the fileref Invent) and that creates a SAS data set named Perm.Update.

     data perm.update;
        infile invent;
        input Item $ 1-13 IDnum $ 15-19
              InStock 21-22 BackOrd 24-25;
        Total=instock+backord;
     run;

Raw Data File Invent

1---+----10---+----20---+-

Bird Feeder   LG088  3 20

6 Glass Mugs  SB082  6 12

Glass Tray    BQ049 12  6

Padded Hangrs MN256 15 20

Jewelry Box   AJ498 23  0

Red Apron     AQ072  9 12

Crystal Vase  AQ672 27  0

Picnic Basket LS930 21  0

Brass Clock   AN910  2 10

1---+----10---+----20---+-
Bird Feeder LG088 3 20
6 Glass Mugs SB082 6 12
Glass Tray BQ049 12 6
Padded Hangrs MN256 15 20
Jewelry Box AJ498 23 0
Red Apron AQ072 9 12
Crystal Vase AQ672 27 0
Picnic Basket LS930 21 0
Brass Clock AN910 2 10

How SAS Software Processes Programs
When you submit a DATA step, SAS software processes the DATA step and creates a new SAS data set. Let's see exactly how that happens.
A SAS DATA step is processed in two distinct phases:

Descriptor and Data Portions of Data Set

During the compilation phase, each statement is scanned for syntax errors. Most syntax errors prevent further processing of the DATA step.

If the DATA step compiles successfully, then the execution phase begins. A DATA step executes once for each observation in the input data set, unless otherwise directed.

First, let's look at the compilation phase.