如何用规则加入 mysql 中的 3 table？

Question

首先，我有3个table。

Table 1条数据：

tid | type_1 | address_1 | contact_1
----+--------+-----------+-----------+
1   | 4      | No.2123   | 01234567
4   | 4      | No.4567   | 00011234

Table 2条数据：

tid | type_2 | address_2 | contact_2
----+--------+-----------+-----------+
2   | 3      | No.8888   | 7654321

Table3条数据：

tid | subject | desc
----+---------+-------------+
1   | Test 1  | Desc 1
2   | Test 2  | Desc 2
3   | Test 3  | Desc 3
4   | Test 4  | Desc 4

我想这样组合：

tid | subject | type_1 | type_2 | address_1 | address_2 | contact_1 | contact_2 | desc
----+---------+--------+--------+-----------+-----------+-----------+-----------+------
1   | Test 1  | 4      |        | No.2123   |           |01234567   |           | Desc1
2   | Test 2  |        | 3      |           |No.8888    |           |7654321    | Desc2
4   | Test 4  | 4      |        | No.4567   |           |00011234   |           | Desc4

如果 table 1 得到 "tid" 1，那么 table 2 永远不会得到相同的时间。

如果在 table 1 和 table 2 中找不到 tid，则忽略

谢谢！

我之前的代码是：

$query = mysql_query("SELECT table1.*, table2.*, table3.subject, table3.desc, FROM table1 ON table1.tid = table3.tid LEFT JOIN table2 ON table2.tid = table3.tid LEFT JOIN table3 ON table1.tid AND table2.tid = table3.tid");

Answer 1

您所写的JOIN子句格式不正确。你应该这样使用它：

`table1 JOIN table2 ON` your conditions to join the table.

您可以从 here 获得更多关于 JOIN 的信息。所以你可以试试这个：

SELECT table3.tid AS tid,
  t3.subject AS subject,
  t1.type_1 AS type_1,
  t2.type_2 AS type_2,
  t1.address_1 AS address_1,
  t2.address_2 AS address_2,
  t1.contact_1 AS contact_1,
  t2.contact_2 AS contact_2,
  t3.desc AS description
FROM table3 t3 
  INNER JOIN table1 t1 ON t3.tid = t1.tid
  INNER JOIN table2 t2 ON t3.tid = t2.tid

Answer 2

SELECT  
        table1.tid,
        table3.subject,
        table1.type_1,
        NULL AS type_2,
        table1.address_1,
        NULL AS address_2,
        table1.contact_1,
        NULL AS contact_2,
        table3.`desc`

FROM table1 
INNER JOIN table3 ON table1.tid=table3.tid
UNION ALL
SELECT  
        table2.tid,
        table3.subject,
        NULL AS type_1,
        table2.type_2,
        NULL AS address_1,
        table2.address_2,
        NULL AS contact_1,
        table2.contact_2,
        table3.`desc`

FROM table2 
INNER JOIN table3 ON table2.tid=table3.tid

Answer 3

DROP TABLE IF EXISTS table1;
CREATE TABLE table1
(tid INT NOT NULL
,type_1 INT NOT NULL
,address_1 VARCHAR(12) NOT NULL
,contact_1 VARCHAR(12) NOT NULL
);


INSERT INTO table1 VALUES
(1   ,4      ,'No.2123','01234567'),
(4   ,4      ,'No.4567','00011234');

DROP TABLE IF EXISTS table2;
CREATE TABLE table2
(tid INT NOT NULL
,type_2 INT NOT NULL
,address_2 VARCHAR(12) NOT NULL
,contact_2 VARCHAR(12) NOT NULL
);

INSERT INTO table2 VALUES
(2   ,3      ,'No.8888','7654321');

DROP TABLE IF EXISTS table3;
CREATE TABLE table3
(tid INT NOT NULL
,subject VARCHAR(12) NOT NULL
,description VARCHAR(12) NOT NULL
);

INSERT INTO table3 VALUES
(1   ,'Test 1','Desc 1'),
(2   ,'Test 2','Desc 2'),
(3   ,'Test 3','Desc 3'),
(4   ,'Test 4','Desc 4');

SELECT x.*
     , y.subject
     , y.description
  FROM 
     ( SELECT tid
            , type_1
            , NULL type_2
            , address_1
            , contact_1
            , NULL address_2
            , NULL contact_2 
         FROM table1
        UNION
       SELECT tid
            , NULL 
            , type_2
            , NULL
            , NULL
            , address_2
            , contact_2 
         FROM table2
    ) x
 JOIN table3 y
   ON y.tid = x.tid;

+-----+--------+--------+-----------+-----------+-----------+-----------+---------+-------------+
| tid | type_1 | type_2 | address_1 | contact_1 | address_2 | contact_2 | subject | description |
+-----+--------+--------+-----------+-----------+-----------+-----------+---------+-------------+
|   1 |      4 |   NULL | No.2123   | 01234567  | NULL      | NULL      | Test 1  | Desc 1      |
|   2 |   NULL |      3 | NULL      | NULL      | No.8888   | 7654321   | Test 2  | Desc 2      |
|   4 |      4 |   NULL | No.4567   | 00011234  | NULL      | NULL      | Test 4  | Desc 4      |
+-----+--------+--------+-----------+-----------+-----------+-----------+---------+-------------+
3 rows in set (0.00 sec)

如何用规则加入 mysql 中的 3 table？

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