tests whether the condition
is true. If it is true, then SAS continues processing the current
observation. If it is false, then SAS stops processing the observation
and returns to the beginning of the DATA step. This type of IF statement
is called a subsetting IF statement because it produces a subset of
the original observations.
IF condition THEN action;
<ELSE action;>
tests whether condition
is true. If it is true, then the action in the THEN clause is executed.
If the condition is false and an ELSE statement is present, the ELSE
action is executed. If the condition is false and no ELSE statement
is present, then execution proceeds to the next statement in the DATA
step.
SET SAS-data-set (IN=variable) SAS-data-set-list;
creates a variable
that is associated with a SAS data set. The value of variable is
1 if the data set has contributed to the observation currently in
the program data vector. The value is 0 if it has not. The IN= variable
exists only while the DATA step executes. It is not written to the
output data set.
You can use the IN=
option with any data set that you name in the SET, MERGE, MODIFY,
or UPDATE statement, but use a different variable name for each one.
SET SAS-data-set-list
END=variable;
creates a variable
whose value is 0 until the DATA step starts to process its last observation.
When processing of the last observation begins, the value of variable changes
to 1. The END= variable exists only while the DATA step executes.
It is not written to the output data set.
You can also use the
END= option with the MERGE, MODIFY, and UPDATE statements.