DROP= Data Set Option
For an input data set, excludes the specified columns
from processing; for an output data set, excludes the specified columns
from being written to the data set.
| Valid in: |
DATA and PROC steps |
| Category: |
Variable Control |
| Supports: |
All |
Syntax
Syntax Description
- column(s)
-
lists one or more column
names. You can list the columns in any form that SAS allows.
Details
If the
option is associated with an input data set, the columns are not available
for processing. If the DROP= data set option is associated with an
output data set, SAS does not write the columns to the output data
set, but they are available for processing.
Comparisons
-
The DROP= data set option differs
from the DROP statement in these ways:
-
In DATA steps, the DROP= data set
option can apply to both input and output data sets. The DROP statement
applies only to output data sets.
-
In DATA steps, when you create
multiple output data sets, use the DROP= data set option to write
different columns to different data sets. The DROP statement applies
to all output data sets.
-
In PROC steps, you can use only
the DROP= data set option, not the DROP statement.
-
The KEEP= data set option specifies
a list of columns to be included in processing or to be written to
the output data set.
Examples
Example 1: Excluding Columns from Input
In this
example, the columns SALARY and GENDER are not included in processing
and they are not written to either output data set:
data payroll;
input idnum $3. +3 gender $1. +4 jobcode $3. +9 salary 5.
+2 birth date7. +2 hired date7.;
informat birth date7. hired date7.;
format birth date7. hired date7.;
datalines;
919 M TA2 34376 12SEP60 04JUN87
653 F ME2 35108 15OCT64 09AUG90
400 M ME1 29769 05NOV67 16OCT90
350 F FA3 32886 31AUG65 29JUL90
401 M TA3 38822 13DEC50 17NOV85
499 M ME3 43025 26APR54 07JUN80
101 M SCP 18723 06JUN62 01OCT90
333 M PT2 88606 30MAR61 10FEB81
402 M TA2 32615 17JAN63 02DEC90
479 F TA3 38785 22DEC68 05OCT89
403 M ME1 28072 28JAN69 21DEC91
739 M PT1 66517 25DEC64 27JAN91
658 M SCP 17943 08APR67 29FEB92
428 F PT1 68767 04APR60 16NOV91
782 M ME2 35345 04DEC70 22FEB92
244 M ME2 36925 31AUG63 17JAN88
383 M BCK 25823 25JAN68 20OCT92
574 M FA2 28572 27APR60 20DEC92
789 M SCP 18326 25JAN57 11APR78
404 M PT2 91376 24FEB53 01JAN80
437 F FA3 33104 20SEP60 31AUG84
639 F TA3 40260 26JUN57 28JAN84
269 M NA1 41690 03MAY72 28NOV92
065 M ME2 35090 26JAN44 07JAN87
876 M TA3 39675 20MAY58 27APR85
037 F TA1 28558 10APR64 13SEP92
129 F ME2 34929 08DEC61 17AUG91
988 M FA3 32217 30NOV59 18SEP84
405 M SCP 18056 05MAR66 26JAN92
430 F TA2 32925 28FEB62 27APR87
983 F FA3 33419 28FEB62 27APR87
134 F TA2 33462 05MAR69 21DEC88
118 M PT3 111379 16JAN44 18DEC80
438 F TA3 39223 15MAR65 18NOV87
125 F FA2 28888 08NOV68 11DEC87
475 F FA2 27787 15DEC61 13JUL90
117 M TA3 39771 05JUN63 13AUG92
935 F NA2 51081 28MAR54 16OCT81
124 F FA1 23177 10JUL58 01OCT90
422 F FA1 22454 04JUN64 06APR91
616 F TA2 34137 01MAR70 04JUN93
406 M ME2 35185 08MAR61 17FEB87
120 M ME1 28619 11SEP72 07OCT93
094 M FA1 22268 02APR70 17APR91
389 M BCK 25028 15JUL59 18AUG90
905 M PT1 65111 16APR72 29MAY92
407 M PT1 68096 23MAR69 18MAR90
114 F TA2 32928 18SEP69 27JUN87
410 M PT2 84685 03MAY67 07NOV86
439 F PT1 70736 06MAR64 10SEP90
409 M ME3 41551 19APR50 22OCT81
408 M TA2 34138 29MAR60 14OCT87
121 M ME1 29112 26SEP71 07DEC91
991 F TA1 27645 07MAY72 12DEC92
102 M TA2 34542 01OCT59 15APR91
356 M ME2 36869 26SEP57 22FEB83
545 M PT1 66130 12AUG59 29MAY90
292 F ME2 36691 28OCT64 02JUL89
440 F ME2 35757 27SEP62 09APR91
368 M FA2 27808 11JUN61 03NOV84
369 M TA2 33705 28DEC61 13MAR87
411 M FA2 27265 27MAY61 01DEC89
113 F FA1 22367 15JAN68 17OCT91
704 M BCK 25465 30AUG66 28JUN87
900 M ME2 35105 25MAY62 27OCT87
126 F TA3 40899 28MAY63 21NOV80
677 M BCK 26007 05NOV63 27MAR89
441 F FA2 27158 19NOV69 23MAR91
421 M TA2 33155 08JAN59 28FEB90
119 M TA1 26924 20JUN62 06SEP88
834 M BCK 26896 08FEB72 02JUL92
777 M PT3 109630 23SEP51 21JUN81
663 M BCK 26452 11JAN67 11AUG91
106 M PT2 89632 06NOV57 16AUG84
103 F FA1 23738 16FEB68 23JUL92
477 M FA2 28566 21MAR64 07MAR88
476 F TA2 34803 30MAY66 17MAR87
379 M ME3 42264 08AUG61 10JUN84
104 M SCP 17946 25APR63 10JUN91
009 M TA1 28880 02MAR59 26MAR92
412 M ME1 27799 18JUN56 05DEC91
115 F FA3 32699 22AUG60 29FEB80
128 F TA2 32777 23MAY65 20OCT90
442 F PT2 84536 05SEP66 12APR88
417 M NA2 52270 27JUN64 07MAR89
478 M PT2 84203 09AUG59 24OCT90
673 M BCK 25477 27FEB70 15JUL91
839 F NA1 43433 29NOV70 03JUL93
;data myfiles.plan1 myfiles.plan2;
set myfiles.payroll (drop=salary gender);
if hired <'01jan98'd then output myfiles.plan1;
else output myfiles.plan2;
run;
proc print data=myfiles.plan1(obs=2);
title 'plan1';
proc print data=myfiles.plan2(obs=2);
title 'plan2';
run;
You cannot
use SALARY or GENDER in any logic in the DATA step because DROP= prevents
the SET statement from reading them from PAYROLL.
Example 2: Processing Columns without Writing Them to a Data Set
In this
example, SALARY and GENDER are not written to PLAN2, but they are
written to PLAN1:
data myfiles.plan1 myfiles.plan2 (drop=salary gender);
set myfiles.payroll;
if hired <'01jan98'd then output myfiles.plan1;
else output myfiles.plan2;
run;