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CREATE VIEW sales_view AS

SELECT salesperson, product, sale_amount

FROM sales

GROUP BY salesperson, product;

CREATE VIEW sales_view AS

SELECT salesperson, product, AVG(sale_amount) AS total_sales

FROM sales

GROUP BY salesperson, product;

CREATE VIEW sales_view AS

SELECT salesperson, product, MAX(sale_amount) AS total_sales

FROM sales

GROUP BY salesperson, product;

Suppose you have two tables in a PostgreSQL database, customers and orders, with the following data:

customers table:

customer_id	customer_name	address	city
1	John Smith	123 Main St.	Anytown
2	Jane Doe	456 Oak St.	Other town
3	Bob Johnson	789 Maple Ave.	Another town

orders table:

order_id	customer_id	order_date	total_amount
1	1	2022-03-01	150.00
2	2	2022-03-02	75.00
3	1	2022-03-03	25.00
4	3	2022-03-04	50.00

Which of the following CREATE VIEW statements would create a vertical view that displays the customer name, order ID, and total amount for all orders?

CREATE VIEW customer_orders_view AS

SELECT customer_name, order_id, total_amount

FROM customers, orders

WHERE customers.customer_id = orders.customer_id

GROUP BY customers.customer_id;

CREATE VIEW customer_orders_view AS

SELECT c.customer_name, o.order_id, o.total_amount

FROM customers c

JOIN orders o ON c.customer_id = o.customer_id;

CREATE VIEW customer_orders_view AS

SELECT customer_name, order_id, total_amount

FROM customers

LEFT JOIN orders ON customers.customer_id = orders.customer_id;

CREATE VIEW customer_orders_view AS

SELECT c.customer_name, o.order_id, o.total_amount

FROM customers c

LEFT JOIN orders o ON c.customer_id = o.customer_id;

Suppose you have a PostgreSQL database that contains three tables, orders, order_details and customers. The orders table contains basic information about each order, including the order ID and customer ID, customers table contains information about customer, while the order_details table contains the details of each order, including the product ID, quantity, and price. You want to create a view that shows the order ID, customer name, product name, quantity, and price for all orders.

Example of the orders table:

order_id	customer_id	order_date
1	1	2022-03-01
2	2	2022-03-02
3	1	2022-03-03
4	3	2022-03-04

Example of the order_details table:

order_id	product_id	quantity	price
1	1	3	10.00
2	2	5	15.00
1	3	2	20.00
4	1	1	8.50

Example of the customers table:

customer_id	customer_name	city
1	Laurence Lebihan	London
2	Diego Roel	Madrid

Which of the following CREATE VIEW statements would accomplish this?

CREATE VIEW order_details_view AS

SELECT o.order_id, c.customer_name, d.product_name, d.quantity, d.price

FROM orders o, order_details d, customers c

WHERE o.order_id = d.order_id

AND o.customer_id = c.customer_id;

CREATE VIEW order_details_view AS

SELECT o.order_id, c.customer_name, d.product_name, d.quantity, d.price

FROM orders o

JOIN order_details d ON o.order_id = d.order_id

JOIN customers c ON o.customer_id = c.customer_id;

CREATE VIEW order_details_view AS

SELECT order_id, customer_name, product_name, quantity, price

FROM orders

JOIN order_details ON orders.order_id = order_details.order_id

JOIN customers ON orders.customer_id = customers.customer_id;

CREATE VIEW order_details_view AS

SELECT order_id, customer_name, product_name, quantity, price

FROM orders

INNER JOIN order_details ON orders.order_id = order_details.order_id

INNER JOIN customers ON orders.customer_id = customers.customer_id;

Suppose you have two tables in a PostgreSQL database, orders and products. You want to create a view that shows the order ID, product name, and quantity for all orders that include a particular product. Which of the following CREATE VIEW statements would accomplish this?

Table Example:

orders table:

| order_id | product_id | quantity |

|----------|------------|----------|

| 1 | 1 | 3 |

| 2 | 2 | 5 |

| 3 | 1 | 2 |

| 4 | 3 | 1 |

products table:

| id | product_name |

|----|--------------|

| 1 | Widget A |

| 2 | Widget B |

| 3 | Widget C |

CREATE VIEW order_product AS

SELECT order_id, product_name, quantity

FROM orders

JOIN products ON orders.product_id = products.id

WHERE product_name = 'example_product';

CREATE VIEW order_product AS

SELECT orders.order_id, products.product_name, orders.quantity

FROM orders, products

WHERE orders.product_id = products.id

AND products.product_name = 'example_product';

CREATE VIEW order_product AS

SELECT order_id, product_name, quantity

FROM orders

JOIN products ON orders.product_id = products.id

HAVING product_name = 'example_product';

CREATE VIEW order_product AS

SELECT orders.order_id, products.product_name, orders.quantity

FROM orders, products

WHERE orders.product_id = products.id

AND products.product_name LIKE '%example_product%';

What is the difference between a regular view and a materialized view in PostgreSQL?

Regular views are read-only, while materialized views allow data modification

Regular views store data physically on disk, while materialized views are virtual

Materialized views are not updated automatically when underlying data changes, while regular views always reflect real-time data

There is no difference; both terms are used interchangeably in PostgreSQL

What is the benefit of using materialized (indexed) views?

They can combine data from one or more base tables (or views) into a new virtual table

They can help to simplify complex queries and join data from multiple tables

They can materialize (persist) the the results of view in a table-like form

They can join horizontally partitioned data from one or more base tables across one or more servers

Which type of view combines data from one or more base tables (or views) into a new virtual table?

Standard views

Indexed views

Partitioned views

Logical views

What is a SQL View?

A physical table that stores data

A query that retrieves and displays data from one or more tables

A stored procedure that performs a set of operations on data

A group of related tables that are linked together

What is the correct syntax for deleting records from table_name with a specific condition in PostgreSQL?

DELETE WHERE condition from table_name;

DELETE FROM table_name WHERE condition;

100%

DELETE SET column = value WHERE condition;

DELETE WHERE condition SET column = value;

Suppose you have a table named sales with columns id, product_name, quantity, and price. You want to update the column total_price by multiplying the quantity and price columns. Which SQL statement will achieve this?

UPDATE sales SET total_price = quantity * price;

100%

UPDATE FROM sales SET total_price = (quantity * price);

UPDATE TABLE sales SET total_price = quantity * price;

UPDATE sales SET total_price = quantity - price;