连接两个表（其中一个是另一个的一部分）

Question

我有两个表表-A和表-B，我想加入这些表格optain Table_c作为结果：

表-A：

+-----------+-----------+---------+ 
| tableA_id | tableB_id | v_id | 
+-----------+-----------+---------+ 
| 1   | 2   | 27  | 
| 2   | 3   | 27  | 
| 3   | 3   | 28  | 
| 4   | 1   | 26  | 
| 5   | 2   | 26  | 
| 6   | 3   | 26  | 
| 7   | 1   | 24  | 
| 8   | 1   | 25  | 
+-----------+-----------+---------+ 

表-B：

+-----------+-----------+ 
| tableB_id | s_name | 
+-----------+-----------+ 
| 1   | s1  | 
| 2   | s2  | 
| 3   | s3  | 
+-----------+-----------+ 

Table_c：

+-----------+-----------+-----------++--------+ 
| tableB_id | s_name | tableA_id | v_id | 
+-----------+-----------+-----------+---------+ 
| 1   | s1  | null  | null | 
| 2   | s2  | 1   | 27  | 
| 3   | s3  | 2   | 27  | 
+-----------+-----------+-----------+---------+ 

我尝试了不同的查询，但我无法达到所需的输出。 这是MYSQL查询：*编辑：反转表顺序。

SELECT s.tableB_id, s.s_name, v.tableA_id, v.v_id 
FROM Table_B as s 
left OUTER JOIN Table_A as v 
ON v.v_id=27 

编辑： 结果应该是左边的所有表-B的数据，并分配给它TABLE_A数据，如果任何或使其无效。我怎样才能做到这一点？

最后编辑： 这里是我想出了一个解决方案：

SELECT s.tableB_id , s.s_name, v.tableA_id, v.v_id 
FROM Table_B s , Table_A v 
WHERE v.v_id=27 AND v.tableB_id = s.tableB_id 

UNION 

SeLECT s.tableB_id , s.s_name, null as tableA_id, null as v_id 
FROM Table_B s 
WHERE s.tableB_id NOT IN (SELECT s.tableB_id 
FROM Table_B s , Table_A v 
WHERE v.v_id=27 AND v.tableB_id = s.tableB_id) 

Answer 1

你可以尝试：

SELECT tb.tableB_id, tb.s_name, ta.tableA_id, ta.v_id 
FROM Table_B tb LEFT JOIN Table_A ta 
    ON tb.tableB_id = ta.tableB_id 

只能选择一个，你可以使用：

SELECT tb.tableB_id, tb.s_name, ta.tableA_id, ta.v_id 
FROM Table_B tb LEFT JOIN 
(SELECT * FROM Table_A 
WHERE v_id = 27) ta 
    ON tb.tableB_id = ta.tableB_id 

Answer 2

SELECT distinct s.tableB_id, s.s_name, v.tableA_id, v.v_id 
FROM Table_A as v 
left OUTER JOIN Table_B as s 
ON v.tableB_id =s.tableB_id and v.v_id = 27; 

Answer 3

使用此查询的希望完全你会得到结果

SELECT s.tableB_id, s.s_name, v.tableA_id, v.v_id 
FROM Table_A as v 
left OUTER JOIN Table_B as s ON s.tableB_id=v.tableB_id 
WHERE v.v_id=27 

Answer 4

顺序颠倒，使之b LEFT JOIN a并添加条件的公共列（tableB_id）：

SELECT s.tableB_id, s.s_name, v.tableA_id, v.v_id 
FROM Table_B as s 
    LEFT OUTER JOIN Table_A as v 
    ON v.tableB_id = s.tableB_id 
    AND v.v_id=27 ;