Question

我正在使用innodb是id_name-＆gt;的外键name.id和id_street-＆gt; street.id 我希望从名称表中获取名称和号码，具体取决于街道＆amp;使用关系表从街道表拉链但我不知道我应该使用的SQL查询。

    Name                      Street                    Relationship
___________ _______      ______________ ____       __________________________
|id  |name | number|     |id  | street |zip |      |id | id_name | id_street |    
|____|_____|_______|     |____|________|____|      |___|_____________________|  
|1   | aaa | 11111 |     |1   | s1     |600 |      |1  | 1       |  1        |                   
|2   | bbb | 11112 |     |2   | s2     |600 |      |2  | 1       |  2        |
|3   | ccc | 11113 |     |3   | s3     |600 |      |3  | 2       |  3        |

我应该使用多个查询：

- 1)get the id of the street/zip (ex: s2 and 600 return=2 )
- 2)get the id of the name (1) from the returned id (2)
- 3) select name/number field from name id (1)

或者可以合并所有查询。

Answer 1

使用此查询：

SELECT name.name, name.number FROM name
    JOIN relationship AS r ON name .id = r.id_name 
    JOIN street ON street.id = r.id_street
    WHERE street.street = "yourStreet" AND street.zip="1111";

Answer 2

您可以通过应用多个连接来实现结果

SELECT 
       N.name,n.number
FROM 
       Name N,
       Street S,
       Relationship R
WHERE
       N.id = R.id_name
AND
       S.id = R.id_street 
AND
       R.id_street = 2 (Displays data only Street ID 2)

您可以添加更多自定义条件来过滤并通过别名选择所需的列

另一个查询中的SQL结果查询

2 个答案: