SAS 9.4 Language Reference, 3rd Edition

statement. The group of language statements contains other programming statements that

manipulate existing SAS data sets or create SAS data sets from raw data files.

You can use the DATA step for the following tasks:

• creating SAS data sets (SAS data files or SAS views)

• creating SAS data sets from input files that contain raw data (external files)

• creating new SAS data sets from existing ones by subsetting, merging, modifying,

and updating existing SAS data sets

• analyzing, manipulating, or presenting your data

• computing the values for new variables

• report writing, or writing files to disk or tape

• retrieving information

• file management

Note: A DATA step creates a SAS data set. This data set can be a SAS data file or a

SAS view. A SAS data file stores data values while a SAS view stores instructions

for retrieving and processing data. When you can use a SAS view as a SAS data file,

as is true in most cases, this documentation uses the broader term SAS data set.

Overview of DATA Step Processing

Flow of Action

When you submit a DATA step for execution, it is first compiled and then executed. The

following figure shows the flow of action for a typical SAS DATA step.

380 Chapter 18 • DATA Step Processing

Figure 18.1 Flow of Action in the DATA Step

data-reading

statement:

is there a

record to read?

reads

an input record

executes

additional

executable statements

writes

an observation to

the SAS data set

returns

to the beginning of

the DATA step

compiles

SAS statements

(includes syntax checking)

creates

an input buffer

a program data vector

descriptor information

begins

with a DATA statement

(counts iterations)

sets

variable values

to missing in the

program data vector

closes

data set;

goes on to the next

DATA or PROC step

NO

YES

Compile Phase

Execution Phase

Overview of DATA Step Processing 381