Creating List Reports
explained how to use a BY
statement in PROC SORT to sort observations and in PROC PRINT to
group observations for subtotals. You can also use the BY statement
in the DATA step to group observations for processing.
When you use the BY statement
with the SET statement,
the data sets that are listed in
the SET statement must be sorted by the values of the BY
variable(s), or they must have an appropriate index.
the DATA step creates two temporary variables for each BY variable. One is named FIRST.variable, where variable is the name of the BY variable, and the other is named LAST.variable. Their ...