In SAS, how do I merge two data sets?

To merge two or more data sets in SAS, you must first sort both data sets by a shared variable upon which the merging will be based. Then use the MERGE statement in your DATA statement.

If you merge data sets without sorting, called one-to-one merging, data of the merged file overwrites the primary data set without considering whether or not two observations are the same.

For example, suppose you have two data sets (one and two below), with a common variable, id. The SAS codes below show how they can be sorted and merged:

In the example above, data set three is created by merging data sets one and two. It will have five variables (id, and v1 to v4) and four cases. Where id=4, variables v1 and v2 will be missing.

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Also see:

• During a SAS session, how do I redirect the work files?
• In SAS, how can I randomly assign half the cases to one group and the remaining half to another?
• In SAS, how do I convert data sets to a format LIMDEP can use?
• In SAS, how do I create a permanent SAS data file?
• In SAS, how do I access a permanent data set stored on a disk?