January 2019
Beginner
556 pages
14h 19m
English
Content preview from Learning PostgreSQL 11 - Third Edition
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The FROM clause
The source of the rows for a query is specified after the FROM keyword. It's called the FROM clause. The query can select rows from zero, one, or more sources. When no source is specified, the FROM keyword should be omitted. A source of the rows for a query can be any combination of the following:
- Tables
- Views
- Functions
- Subqueries
- VALUES clauses
When multiple sources are specified, they should be separated by a comma or the JOIN clause should be used.
It's possible to set aliases for tables in the FROM clause. The optional AS keyword is used for that:
car_portal=> SELECT a.car_id, a.number_of_doors FROM car_portal_app.car AS a; car_id | number_of_doors --------+----------------- 1 | 5 2 | 3 3 | 5 ...
In the preceding ...
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