DROP= Data Set Option

For an input data set, excludes the specified variables from processing; for an output data set, excludes the specified variables from being written to the data set.
Valid in: DATA step and PROC steps
Category: Variable Control
Syntax
Details
Comparisons
Examples
Example 1: Excluding Variables from Input
Example 2: Processing Variables without Writing Them to a Data Set
See Also

Syntax

DROP=variable-1 <...variable-n>

Syntax Description

variable-1 <...variable-n>
lists one or more variable names. You can list the variables in any form that SAS allows.

Details

If the option is associated with an input data set, the variables are not available for processing. If the DROP= data set option is associated with an output data set, SAS does not write the variables 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 variables 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 variables to be included in processing or to be written to the output data set.

Examples

Example 1: Excluding Variables from Input

In this example, the variables SALARY and GENDER are not included in processing and they are not written to either output data set: 
data plan1 plan2;
   set payroll(drop=salary gender);
   if hired<'01jan98'd then output plan1;
   else output 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 Variables 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 plan1 plan2(drop=salary gender);
   set payroll; 
   if hired<'01jan98'd then output plan1;
   else output plan2;
run;

See Also

Data Set Options:
KEEP= Data Set Option
Statements:
DROP Statement in SAS Statements: Reference
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