MySQL的選擇與同一列不同的where子句

Question

我有一個MySQL表由這些列中出現兩次：

USER_ID，開始，結束，區

每個用戶ID在開始和結束值各地區，像這樣：

+-----------------------------------+ 
| user_id | start | end | district | 
|  1 | 1000 | 2000 | north | 
|  1 | 1200 | 2200 | south | 
|  2 | 900 | 1900 | north | 
|  2 | 950 | 1700 | south | 
+-----------------------------------+ 

我要尋找一個選擇具有每USER_ID一行結果，其中列出了每兩個區的開始和結束。像

select user_id, 
(start as no_st, end as no_en where district='north'), 
(start as so_st, end as so_en where district='south'); 

東西給：

+-----------------------------------------+ 
| user_id | no_st | no_en | so_st | so_en | 
|  1 | 1000 | 2000 | 1200 | 2200 | 
|  2 | 900 | 1900 | 950 | 1700 | 
+-----------------------------------------+ 

是否有這種神奇的查詢？

感謝， 巴特......

Answer 1

這是一個支點查詢一個解決方案：

SELECT user_id, 
    MAX(IF(district='north', start, null)) AS no_st, 
    MAX(IF(district='north', end, null)) AS no_en, 
    MAX(IF(district='south', start, null)) AS so_st, 
    MAX(IF(district='south', end, null)) AS so_en 
FROM `NoOneEverNamesTheirTableInSQLQuestions` 
GROUP BY user_id;