The UNION operator in Proc SQL is used to append the rows of two or more SELECT statements having the same number of columns with similar data types. Similar columns in each SELECT statement should normally be in the same order, as the Union is done by position not by column name, except where appending dissimilar columns from a select statement is explicitly desired.
Note that, unlike using the SET statement with multiple datasets, the default behavior of the UNION operator is to remove duplicate rows, from the results of each SELECT statement as well as overall, resulting in only DISTINCT rows. If retention of duplicate rows is desired, either OUTER UNION must be specified, or else the ALL operator must be used on individual SELECT statements where duplicates are desired.
SELECT column_name(s) FROM table_name1 <OUTER> UNION <ALL> SELECT column_name(s) FROM table_name2 ...
This article was originally posted by Gerald Zuckier on sasCommunity.org.
Are you ready for the spotlight? We're accepting content ideas for SAS Innovate 2025 to be held May 6-9 in Orlando, FL. The call is open until September 25. Read more here about why you should contribute and what is in it for you!
Data Literacy is for all, even absolute beginners. Jump on board with this free e-learning and boost your career prospects.