| WHERE-Expression Processing |
-
WHERE-expression processing
-
enables you to conditionally select a subset
of observations, so that SAS processes only the observations that meet a set
of specified conditions. For example, if you have a SAS data set that contains
sales records, you might want to print just the subset of observations for
which the sales are greater than $300,000 but less than $600,000. In addition,
WHERE-expression processing can improve efficiency of a request. For example,
if a WHERE expression can be optimized with an index, it is not necessary
for SAS to read all observations in the data set in order to perform the request.
-
WHERE
expression
-
defines a condition that selected observations
must satisfy in order to be processed. You can have a single WHERE expression,
referred to as a simple expression, such as the following:
where sales gt 600000;
Or you can have multiple WHERE
expressions, referred to as a compound expression, such as the
following:
where sales gt 600000 and salary lt 100000;
 |
|
Copyright © 2010 by SAS Institute Inc., Cary, NC, USA. All rights reserved.