January 2019
Beginner
556 pages
14h 19m
English
Content preview from Learning PostgreSQL 11 - Third Edition
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Set operations – UNION, EXCEPT, and INTERSECT
Set operations are used to combine the results of several queries. This is different from joining, although the same results can often be achieved with joining. Simply speaking, joining means placing the records of two tables beside each other horizontally. The result of joining is that the number of columns equals the sum of the number of columns in the source tables, and the number of records will depend on the join conditions.
Combining, in contrast, means putting the result of one query on top of the result of another query vertically. The number of columns stays the same, but the number of rows is the sum of the rows from the sources.
There are three set operations:
- UNION: Appends the result ...
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