sqlite LEFT OUTER JOIN多个表

Question

在这个例子中,我们在SQLite数据库上有3个相关的表:

CREATE TABLE test1 (
    c1 integer,
    primary key (c1)
);
CREATE TABLE test2 (
    c1 integer,
    c2 integer,
    primary key (c1, c2)
);    
CREATE TABLE test3 (
    c2 integer,
    c3 integer,
    primary key (c2)
);

现在我需要加入所有表格:

 test1 -> test2 (with c1 column)
          test2 -> test3 (with c2 column).

我试过这个解决方案,但它没有运行:

SELECT 
   * 
   FROM test1 a 
        LEFT OUTER JOIN test2 b
                        LEFT OUTER JOIN test3 c
                          ON c.c2 = b.c2 
          ON b.c1=a.c1 

它给了我一个错误: near "ON": syntax error.

有帮助吗？

Answer 1

这是你的ON陈述的简单错位.这符合SQL标准:

SELECT * 
FROM test1 a 
LEFT OUTER JOIN test2 b ON b.c1=a.c1 
LEFT OUTER JOIN test3 c ON c.c2=b.c2 

这在此进一步深入解释.