Column References#

A column can be referenced in the form:

[correlation.]column_name

where correlation could be:

  • a table name (possibly qualified with a schema name)

  • an alias for a table

  • omitted if column_name is unique across all tables in the query.

mydb=> SELECT p.product_name, p.unit_price AS buying_price,
mydb->        public.products.price AS selling_price, items_in_stock, last_delivery_date
mydb->   FROM purchases p JOIN products ON p.product_name = products.name
mydb->   LIMIT 5;
 product_name | buying_price | selling_price | items_in_stock | last_delivery_date 
--------------+--------------+---------------+----------------+--------------------
 Apples       |        23.80 |         25.00 |            100 | 2023-07-24
 Apples       |        24.10 |         25.00 |            100 | 2023-07-25
 Apples       |        23.50 |         25.00 |            100 | 2023-07-28
 Bananas      |         8.50 |         10.00 |             32 | 2023-07-23
 Bananas      |         9.00 |         10.00 |             32 | 2023-07-25
(5 rows)