NW5-Prep-work-Khadar-DBW1

db/week-1/sql/-- Exercise 4 -to - 5.pgsql

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+-- Exercise 4
+--4.1
+SELECT * FROM reservations WHERE checkout_date - checkin_date >0;
+
+--4.2
+
+SELECT rate*5 AS "5 Nights No Discount", rate*0.15*5 AS "Discount",  rate*5 - rate*0.15*5 AS "Discounted Rate for 5 Nights" 
+FROM rooms 
+WHERE room_type ILIKE 'premier' OR room_type ILIKE 'premier plus';
+
+--4.3
+select * from reservations 
+where checkin_date between '2023-01-01' and '2023-02-01';
+
+
+-- Exercise 5
+
+--5.1 
+SELECT DISTINCT room_type FROM rooms;
+
+--5.2
+SELECT name,address,phone FROM customers ORDER BY name;
+
+--5.3
+SELECT name, address,city,country FROM customers ORDER BY country, city DESC;
+
+--5.4
+--SELECT room_no,room_type,rate*5 AS "Cost of 5 Nights" FROM rooms ORDER BY rate*5 DESC LIMIT 15; -- this query will work as same the following one.
+SELECT room_no,room_type,rate*5 AS "Cost of 5 Nights" FROM rooms ORDER BY "Cost of 5 Nights" DESC LIMIT 15;

db/week-1/sql/--Exercise 1 -to- 3.pgsql

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+--Exercise 1
+--1.1 List the name, phone , eamil of all customers
+SELECT name,phone,email FROM customers;
+
+--1.2 List all the details of rooms
+SELECT * FROM rooms;
+
+--1.3 List the customersid, checkin date and number of guests from reservations
+SELECT cust_id,checkin_date,no_guests FROM reservations;
+
+-- Exercise 2
+--2.1 \d customers this is how to display a table definition in the terminal
+--2.2 \? select will show all options available under the SELECT command.
+--2.3 \d is one of the informational commands and it shows the list of SEQUENCES
+cyf_hotels=> \ds
+                    List of relations
+ Schema |        Name         |   Type   |     Owner      
+--------+---------------------+----------+----------------
+ public | bookings_id_seq     | sequence | codeyourfuture
+ public | customers_id_seq    | sequence | codeyourfuture
+ public | hotels_id_seq       | sequence | codeyourfuture
+ public | invoices_id_seq     | sequence | codeyourfuture
+ public | reservations_id_seq | sequence | codeyourfuture
+(5 rows)
+
+-- Exercise 3
+--3.1 customers from Norway
+SELECT * FROM customers WHERE country="Norway";
+
+--3.2 rooms that can accommodate more then 2 no_guests
+SELECT * FROM rooms WHERE no_guests > 2;
+
+--3.3 invocies dated back a month ago.
+SELECT * FROM invoices WHERE invoice_date <='2023-01-02';
+
+--3.4 the effect of 15% discount of last MONTH
+SELECT * FROM invoices WHERE invoice_date >= '2023-01-01'; --to see the table data with same period
+
+SELECT sum(total) As "Total Without Discount", 
+sum(total)*0.15 AS "Total Discount", 
+sum(total)-sum(total)*0.15 AS "Discounted Total" 
+from invoices 
+where invoice_date >= '2023-01-01';
+
+--3.5 List of customers names starts with "W"
+
+SELECT * FROM customers WHERE name ILIKE 'm%';
+
+
+