drop/keep vs drop=/keep=

[clqa]

is there any difference in the drop, keep, (drop=), and (keep=) function?

[Cynthia_sas]

Hi:
We cover the use of DROP and KEEP statements versus DROP= and KEEP= options in our Programming 1 and Programming 2 classes. For a discussion of the differences, you might want to look in the documentation.

Cynthia

[Reeza]

Yes. 
DROP/KEEP are STATEMENTS usually only valid in a SAS data step.

DROP=/KEEP= are data set OPTIONS. They can be used almost anywhere you reference a SAS data set including in a SQL step. 

They act at different points of time, for example a KEEP statement in the data step will only keep variables but they're available for calculations. If you use DROP = on a data set that's being read for example that data is not read into the step and cannot be used in calculations. 

data want1 (drop=weight) want2 (drop=height); *variables are dropped for output data sets;

set sashelp.class (drop=age); *age is dropped before the data is read in;

new_name = catt(name, ' Smith');

drop name;*name is dropped for all data sets but is available for calculations;

run;