text: --1
  SELECT “Administrator”.”Name” FROM “DBHotel”.”Administrator” WHERE “NAME” LIKE ‘S%’;
  
  --2
  SELECT "employee"."employee_id", "employee"."employee_surname", "employee"."employee_name" FROM "DBHotel"."employee" 
  JOIN "DBHotel"."Administrator" 
  ON "Administrator"."Admin_id" = "employee"."admin_id" WHERE "Administrator"."Name" = 'Oleg Mihailov';
  
  --3
  SELECT "Guest"."Name" FROM "DBHotel"."Guest" JOIN "DBHotel"."Booking" ON "Guest"."Guest_id" = "Booking"."guest_id" WHERE 
  "Booking"."checkout_date" BETWEEN '2020-05-07' AND '2020-05-09';
  
  --4
  SELECT "Booking"."checkin_date", "Booking"."checkout_date" FROM "DBHotel"."Booking" 
  JOIN "DBHotel"."Guest" ON "Guest"."Guest_id" = "Booking"."guest_id" WHERE "Guest"."Name" LIKE 'N%';
  
  --5
  Select "Administrator"."Name", "Guest"."Name", "Guest"."Where_from" from "DBHotel"."Administrator" JOIN "DBHotel"."Booking" ON "Booking"."admin_id" = "Administrator"."Admin_id" 
  JOIN "DBHotel"."Guest" ON "Guest"."Guest_id" = "Booking"."guest_id" WHERE "Guest"."Where_from" LIKE 'M%';
  
  --6
  Select "employee"."employee_surname", "cleaning_schedule"."floor_number" FROM "DBHotel"."employee" 
  JOIN "DBHotel"."cleaning_schedule" ON "cleaning_schedule"."empoyee_id" = "employee"."employee_id" ORDER BY "floor_number";
  
  --7
  Select "room_type"."Capacity", "room_type"."Price", "Floor"."floor_number" FROM "DBHotel"."room_type" JOIN "Room" ON "Room"."type_id" = "room_type"."type_id" 
  RIGHT JOIN "Floor" ON "Floor"."floor_id" = "Room"."floor_id";
  
  --8
  SELECT COUNT("Booking"."guest_id") FROM "DBHotel"."Booking" JOIN "DBHotel"."Room" ON "Room"."room_id" = "Booking"."room_id" 
  WHERE "Booking"."checkin_date" >= '2020-05-01' AND "Booking"."checkout_date" <= '2020-06-01';
  
  --9
  SELECT COUNT("Room"."room_id"), "Floor"."floor_number" FROM "DBHotel"."Room" 
  JOIN "DBHotel"."Floor" ON "Floor"."floor_id" = "Room"."floor_id" GROUP BY "Floor"."floor_number";
  
  --10
  SELECT "employee"."employee_surname", "cleaning_schedule"."weekday", "cleaning_schedule"."floor_number" FROM "DBHotel"."employee" 
  RIGHT JOIN "DBHotel"."cleaning_schedule" ON "cleaning_schedule"."empoyee_id" = "employee"."employee_id";
  
  --11
  SELECT "Guest"."Name" FROM "DBHotel"."Guest" WHERE 
  EXISTS (SELECT "Booking"."checkin_date" FROM "DBHotel"."Booking" 
  		WHERE "Booking"."guest_id" = "Guest"."Guest_id" AND "Booking"."checkin_date" < '2020-05-06');
  
  --12
  SELECT "Room"."room_id" FROM "DBHotel"."Room" JOIN "DBHotel"."Floor" ON "Floor"."floor_id" = "Room"."floor_id"
  JOIN "DBHotel"."Cleaning" ON "Cleaning"."floor_id" = "Room"."floor_id" 
  WHERE "Cleaning"."cleaning_id" NOT IN(SELECT "Cleaning"."cleaning_id" FROM "DBHotel"."Cleaning" WHERE "Cleaning"."cleaning_date" > '2020-05-03');
  
  --13
  SELECT "Room"."room_id" FROM "DBHotel"."Room" JOIN "DBHotel"."Floor" ON "Floor"."floor_id" = "Room"."floor_id"
  JOIN "DBHotel"."Cleaning" ON "Cleaning"."floor_id" = "Room"."floor_id" 
  WHERE EXISTS(SELECT "Room"."room_id" FROM "DBHotel"."Room" 
  												  JOIN "DBHotel"."Booking" ON "Booking"."room_id" = "Room"."room_id"
  WHERE "Booking"."checkin_date" < '2020-05-05' AND "Cleaning"."cleaning_id" 
  			 NOT IN(SELECT "Cleaning"."cleaning_id" FROM "DBHotel"."Cleaning" 
  						WHERE "Cleaning"."cleaning_date" < '2020-05-06' AND "Cleaning"."cleaning_date" > '2020-05-01'));
  
  --14
  SELECT "Room"."room_id", (MAX("Booking"."checkout_date")) AS checkout_date
  FROM "DBHotel"."Room" LEFT JOIN "DBHotel"."Booking" ON "Booking"."room_id" = "Room"."room_id"
  GROUP BY "Room"."room_id"
  HAVING (((MAX("Booking"."checkout_date"))< '2020-05-10')) OR (((MAX("Booking"."checkout_date")) IS NULL));
  
  --15
  SELECT DISTINCT "room_type"."type_id" AS Room_type, COUNT("Booking"."booking_id") AS Num_bookings, 
  SUM("room_type"."Price") AS living_price, 
  ABS(date("Booking"."checkout_date") - date("Booking"."checkin_date")) AS Amount_of_days, 
  SUM("room_type"."Price" * ABS(date("Booking"."checkout_date") - date("Booking"."checkin_date"))) AS living_cost 
  FROM("DBHotel"."room_type" INNER JOIN ( "DBHotel"."Booking" INNER JOIN "DBHotel"."Room" ON "Room"."room_id" = "Booking"."room_id") 
  	  ON "room_type"."type_id" = "Room"."type_id")
  GROUP BY "room_type"."type_id", "Booking"."checkout_date", "Booking"."checkin_date";
  
  