Using Views - MariaDB Crash Course - page 189

Note
WHERE Clauses and WHERE Clauses If a WHERE clause is used when retrieving data
from the view, the two sets of clauses (the one in the view and the one passed to it) are
combined automatically.
Using Views with Calculated Fields
Views are exceptionally useful for simplifying the use of calculated fields. The
following is a SELECT statement introduced in Chapter 10. It retrieves the
order items for a specific order, calculating the expanded price for each item:
▼ Input
SELECT prod_id,
quantity,
item_price,
quantity*item_price AS expanded_price
FROM orderitems
WHERE order_num = 20005;
▼ Output
+---------+----------+------------+----------------+
| prod_id | quantity | item_price | expanded_price |
+---------+----------+------------+----------------+
| ANV01 | 10 | 5.99 | 59.90 |
| ANV02 | 3 | 9.99 | 29.97 |
| TNT2 | 5 | 10.00 | 50.00 |
| FB | 1 | 10.00 | 10.00 |
+---------+----------+------------+----------------+
To turn this into a view, do the following:
▼ Input
CREATE VIEW orderitemsexpanded AS
SELECT order_num,
prod_id,
quantity,
item_price,
quantity*item_price AS expanded_price
FROM orderitems;
To retrieve the details for order 20005 (the previous output), do the following:
▼ Input
SELECT *
FROM orderitemsexpanded
WHERE order_num = 20005;