SQL - MySQL的：LEFT JOIN在多行并获取1行

Question

我有2个表：

表：电影

MovieID -- Name 
1   -- Movie1 
2   -- Movie2 

表：类型

MovieID -- Type 
1   -- DVD 
1   -- Bluray 
1   -- VCD 
2   -- DVD 

我需要一个查询找出这一行： 电影1：DVD - 蓝光 - VCD

我用过：

条

SELECT Movies.Name, 
IF(TYPE = 'DVD', 1, 0) AS DVD, 
IF(TYPE = 'Bluray', 1, 0) AS Bluray, 
IF(TYPE = 'VCD', 1, 0) AS VCD 
FROM Movies LEFT JOIN Types ON Movies.MovieID = Types.MovieID 

但它返回多盘线：

Movies.Name -- DVD -- Bluray -- VCD 
Movie1   -- 1  -- 0  -- 0 
Movie1   -- 0  -- 1  -- 0 
Movie1   -- 0  -- 0  -- 1 
Movie2   -- 1  -- 0  -- 0 

我想：

Movie1   -- 1  -- 1  -- 1 
Movie2   -- 1  -- 0  -- 0 

Answer 1

的group_concat()功能可能会做的伎俩，在这里。

没有测试，但我想这样的事情应该工作：

SELECT Movies.Name, 
    group_concat(type separator ' - ') as type 
FROM Movies 
    LEFT JOIN Types ON Movies.MovieID = Types.MovieID 
group by Movies.Name 

Answer 2

假设你想单独列返回为每种类型：

SELECT m.Name, 
     SUM(CASE WHEN t.Type = 'DVD' THEN 1 ELSE 0 END) AS DVD, 
     SUM(CASE WHEN t.Type = 'Bluray' THEN 1 ELSE 0 END) AS Bluray, 
     SUM(CASE WHEN t.Type = 'VCD' THEN 1 ELSE 0 END) AS VCD 
    FROM Movies m 
     LEFT JOIN Types t 
      ON m.MovieID = t.MovieID 
    GROUP BY m.Name 

Answer 3

 
SELECT m.Name, 
IF(t1.Type IS NOT NULL, 1, 0) as DVD, 
IF(t2.Type IS NOT NULL, 1, 0) as Bluray, 
IF(t3.Type IS NOT NULL, 1, 0) as VCD 
FROM Movies m 
LEFT OUTER JOIN Types t1 on m.MovieID = t1.MovieID and t1.Type = 'DVD' 
LEFT OUTER JOIN Types t2 on m.MovieID = t2.MovieID and t2.Type = 'Bluray' 
LEFT OUTER JOIN Types t3 on m.MovieID = t3.MovieID and t3.Type = 'VCD'