Joins observations from two or more SAS data sets into single
observations
| Valid: |
in a DATA step
|
| Category: |
File-handling
|
| Type: |
Executable
|
MERGE SAS-data-set-1
<(data-set-options)>
SAS-data-set-2 <(data-set-options) >
<. . .
SAS-data-set-n<(data-set-options)>>
<END=variable>;
|
-
SAS-data-set(s)
-
names at least two existing SAS data sets
from which observations are read.
-
(data-set-options)
-
specifies one or more SAS data set options
in parentheses after a SAS data set name.
-
END=variable
-
names and creates a temporary variable that
contains an end-of-file indicator.
The MERGE statement is flexible and has a variety of
uses in SAS programming. This section describes basic uses of MERGE. Other
applications include using more than one BY variable, merging more than two
data sets, and merging a few observations with all observations in another
data set.
One-to-one
merging combines observations from two or more SAS data sets into a single
observation in a new data set. To perform a one-to-one merge, use the MERGE
statement without a BY statement. SAS combines the first observation from
all data sets that are named in the MERGE statement into the first observation
in the new data set, the second observation from all data sets into the second
observation in the new data set, and so on. In a one-to-one merge, the number
of observations in the new data set is equal to the number of observations
in the largest data set named in the MERGE statement. See Example 1 for an
example of a one-to-one merge. For more information, see "Reading, Modifying,
and Combining SAS Data Sets" in
SAS Language Reference: Concepts.
- CAUTION:
- Use care when you combine data sets with a one-to-one
merge.
One-to-one merges may sometimes produce
undesirable results. Test your program on representative samples of the data
sets before you use this method.
![[cautend]](../common/images/cautend.gif)
Match-merging
combines observations from two or more SAS data sets into a single observation
in a new data set according to the values of a common variable. The number
of observations in the new data set is the sum of the largest number of observations
in each BY group in all data sets. To perform a match-merge, use a BY statement
immediately after the MERGE statement. The variables in the BY statement must
be common to all data sets. Only one BY statement can accompany each MERGE
statement in a DATA step. The data sets that are listed in the MERGE statement
must be sorted in order of the values of the variables that are listed in
the BY statement, or they must have an appropriate index. See Example 2 for
an example of a match-merge. For more information, see "Reading, Modifying,
and Combining SAS Data Sets" in
SAS Language Reference: Concepts.
This example shows how to combine observations from
two data sets into a single observation in a new data set:
data benefits.qtr1;
merge benefits.jan benefits.feb;
run;
This example shows how to combine observations from
two data sets into a single observation in a new data set according to the
values of a variable that is specified in the BY statement:
data inventry;
merge stock orders;
by partnum;
run;
Copyright © 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.
