MySQL複雜查詢

Question

嘿，我一直在試圖弄清楚如何完成這些查詢。有人可以幫我嗎。 這些是我目前擁有的表格。

BOOKING

HOTEL_NO
GUEST_NO
DATE_FROM DATE_TO
ROOM_NO

來賓

GUEST_NO
GUEST_NAME CITY
ADDRESS
ZIP_CODE

HOTEL

HOTEL_NO
HOTEL_NAME CITY
ADDRESS
ZIP_CODE
STAR

ROOM

ROOM_NO
HOTEL_NO
ROOM_TYPE 價格

這些是我需要做的查詢。

- 列出所有預訂（過去和現在）在同一家酒店的客人。

- 創建一個視圖的VIP客戶，列出誰擁有唯一的四星級酒店或 4星級酒店

-Among貴賓預約的客人找到最大所有的住宿客人（以天數項）。 表達這個查詢與視圖和沒有視圖

有人可以幫我嗎？

Answer 1

這應該讓你開始。發佈在stackoverflow上，你需要提出具體的問題或錯誤或問題。就像你在評論中發佈的查詢頂部....這可能是一個問題本身：「我有這些表，這是一個特定的目標（問題/結果集），我試過這個查詢......它給我這個結果或者給我這個錯誤。「

BOOKING: HOTEL_NO, GUEST_NO, DATE_FROM, DATE_TO, ROOM_NO 

GUEST: GUEST_NO, GUEST_NAME, CITY, ADDRESS, ZIP_CODE 

HOTEL: HOTEL_NO, HOTEL_NAME, CITY, ADDRESS, ZIP_CODE, STAR 

ROOM:  ROOM_NO, HOTEL_NO, ROOM_TYPE, PRICE 

所有客人和預訂...

-- all guests: select * from guest; 
    -- all bookings: select * from booking; 

    select * 
    from  guest 
      join booking on guest.guest_no = booking.guest_no; 

    -- which is the same as... 

    select * 
    from  guest, booking 
    where guest.guest_no = booking.guest_no; 

    -- and... your comments query was missing a group by clause 

    select guest_no, guest_name, count(*) as booking_count 
    from  guest 
      join booking on guest.guest_no = booking.guest_no 
    group by guest_no, guest_name; 

    select guest_no, guest_name, count(distinct hotel_no) as hotel_count 
    from  guest 
      join booking on guest.guest_no = booking.guest_no 
    group by guest_no, guest_name 
    having count(distinct hotel_no) = 1; 

，我count(distinct hotel_no)，因爲......他們可能在賓館A 3周的預訂和1酒店B.基本的加入會給我4那個人的排。我不在乎有多少預訂。我關心有多少家酒店。所以我想要統計每個人（有那個分組）的hotel_no而不是每一行的不同事件。

客人由他們的明星...

-- so we have to get guest and hotel joined. bc hotel has stars. 
    -- booking has hotel_no. so... we can use that last query and 
    -- join in HOTEL to get the star information. in the WHERE you 
    -- will want to put your filter for the number of stars that you 
    -- are looking for =4 or >=4 or something like that. 
    -- you might want to check out DISTINCT to get just a list of names 
    -- instead of a row for each booking. 

天數，他們住的......

-- use the second query. 
    -- datediff(date_to, date_from) as days_stay gives you the length of stay 
    -- i don't know what the view is. 
    -- to get the top length could go two ways... either ORDER BY and LIMIT if there is 
    -- only one person with the top length (let's say 10 days). if there are many people 
    -- who have stayed 10 days, you'll need to do a MAX on the days_stay and either join 
    -- that in or use it in the WHERE as a nested select. 

---

這個假設存在下榻酒店的單項最高長度。只有一個人呆了10天。

SELECT guest_no, guest_name, datediff(date_to, date_from) days_stayed 

FROM vip_guest 

     join booking on vip_guest.guest_no = booking.guest_no 

order by datediff(date_to, date_from) desc 
limit 1,1   

這應該工作了很多...（我沒有測試這些......只是一種看着它）

SELECT distinct guest_no, guest_name, datediff(date_to, date_from) max_stay 

FROM vip_guest 

     join booking on vip_guest.guest_no = booking.guest_no 

where datediff(date_to, date_from) = (
        select max(datediff(date_to, date_from)) as days_stayed 
        from booking) 

嵌套查詢得到了大家的最長停留時間長度。 vip_guest和預訂加在一起給了我們客人和日期imfo。我們將爲每個vip_guest獲得所有預訂。所以我們希望將其過濾到停留長度==最大逗留長度。如果一個人有多個10天的逗留（我的任意最大逗留長度）...使用不同的。

現在...這是一個關於嵌套查詢的好點。我不知道你的觀點是什麼。有可能沒有最大VIP客人逗留，只要最長停留時間。在這種情況下，此查詢將不會返回任何內容。