3表連接從一個表中的一個字段，並從另一個

Question

我有這個疑問

SELECT cities.city, city_time.time_slot 
FROM cities, city_date, city_time 
WHERE city_time.city_date_id = city_date.city_id = city_date.city_id = cities.id 
AND city_time.city_date_id = '1' 

我試圖讓cities.city和city_time.time_slot到同一行的一個領域，他們通過city_date連接，

cities has- 
=========== 
id 
city, 

city_date has 
=========== 
id 
city_id (fk for city_table) 

city_time has 
============== 
city_date_id (FK for city_date table) 
time_slot 

一直在嘗試幾個ways-

SELECT cities.city, city_time.time_slot 
FROM (city_date LEFT JOIN cities ON city_time.city_date_id = city_date.city_id) 
LEFT JOIN city_date ON city_time.city_date_id = city_date.city_id 
WHERE city_time.city_date_id = '1' 

我只是想從城市表的城市字段鏈接到city_time表中的time_slot字段。甚至不需要左連接，但我想我會包括它來幫助你理解我的想法。

Answer 1

從你的其他問題來看，這看起來就是你以後的樣子。
請使用更短的名稱（希望仍然有意義）作爲別名。

SELECT c.city, t.time_slot 
FROM cities c 
LEFT JOIN city_date d on d.city_id = c.id 
LEFT JOIN city_time t on t.city_date_id = d.city_id AND t.city_date_id = '1' 

Answer 2

select c.city, ct.time_slot 
    from cities c 
     inner join city_date cd 
      on c.id = cd.city_id 
     inner join city_time ct 
      on cd.id = ct.city_date_id 
    where ct.city_date_id = 1 

Answer 3

應該有兩個表共同的東西，這樣就可以進行比較，並有你想打印什麼..像添加類似城市標識和城市的時間ID具有相同的記錄。