DROP Statement
- DROP variable-list;
The DROP statement specifies that some variables
be excluded from the OUT= data set. Only the
time series and event variables
can be specified in a DROP statement.
None of the BY variables or the time ID variable DATE can be
excluded from the OUT= data set.
If they are referenced in a DROP statement, a warning message is
given and the reference is ignored.
Use the WHERE statement for selection based on BY variables, and
use the RANGE statement for date selections.
The variable list can contain variable names
or name range specifications.
See the section "Variable Lists" for details.
Only one DROP or one KEEP statements can be used.
KEEP and DROP are mutually exclusive.
There is a default KEEP list for each file type. Usually, descriptor
type variables, like footnotes, are not included in the default KEEP
list. If you specify a DROP statement, the default list becomes
undefined.
You can also use the DROP= data set option
to control which variables to exclude from the OUT= data set.
However, the DROP statement differs from the DROP= data set option in
several aspects:
- The DROP statement selection is applied
before variables are read from the data file,
while the DROP= data set option selection is applied
after variables are read and as they are written to the OUT= data set.
Therefore, using the DROP statement instead of the DROP= data set option
is much more efficient.
- If the DROP statement causes all series variables to be excluded, then
no observations are output to the OUT= data set.
- The DROP statement variable specifications are applied to each cross
section independently. This behavior may produce different
variables than those produced by the DROP= data set option
when order-range variable list specifications are used.
Copyright © 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.
