Question

所以我规范化我的数据库，对于我来说，获取或更新表中的记录似乎相当复杂。我有5个表（details，country，materials，vendor_countries，vendor_materials）。实际上"details"是我的主要表格。

country表有两列（id，name）。
materials表还有两列（id，name）。
details表包含有关供应商的人员信息（name，email，phone，address）。

供应商可能有多个国家/地区和材料，因此我又增加了两个表vendor_countries和vendor_materials，其列为（did，cid），（{{1 }}，did）。 mid是来自"did"表和details的每个供应商的ID，cid是来自国家/地区和材料表的国家/地区ID和材料ID。

现在我想要获取供应商及其国家和材料。

这是我的详细信息表，vendor_countries和vendor_materials表

到目前为止，我提出了一个查询，如下所示：

mid

我得到的结果如下：

哪个不对，它应该在3行中，因为＆＃34; ali＆＃34;供应商在3个国家和3种材料工作。我正在寻找一些智能解决方案，它也不会减慢我的页面速度。提前谢谢。

Answer 1

在没有关于表模式的任何响应的情况下，我尝试根据上面的描述重新创建表 - 使用v_为每个表添加前缀，这样我就可以对这个数据库中的表进行分组并引用{{1} } did（供应商ID）并填充我认为来自问题的样本数据

vid

或更具选择性的查询

mysql> describe v_country;
+-------+------------------+------+-----+---------+----------------+
| Field | Type             | Null | Key | Default | Extra          |
+-------+------------------+------+-----+---------+----------------+
| id    | int(10) unsigned | NO   | PRI | NULL    | auto_increment |
| name  | varchar(50)      | YES  |     | NULL    |                |
+-------+------------------+------+-----+---------+----------------+


mysql> describe v_details;
+---------+------------------+------+-----+---------+----------------+
| Field   | Type             | Null | Key | Default | Extra          |
+---------+------------------+------+-----+---------+----------------+
| id      | int(10) unsigned | NO   | PRI | NULL    | auto_increment |
| vendor  | varchar(50)      | YES  |     | NULL    |                |
| email   | varchar(50)      | YES  |     | NULL    |                |
| phone   | varchar(50)      | YES  |     | NULL    |                |
| address | varchar(50)      | YES  |     | NULL    |                |
+---------+------------------+------+-----+---------+----------------+


mysql> describe v_materials;
+-------+------------------+------+-----+---------+----------------+
| Field | Type             | Null | Key | Default | Extra          |
+-------+------------------+------+-----+---------+----------------+
| id    | int(10) unsigned | NO   | PRI | NULL    | auto_increment |
| name  | varchar(50)      | YES  |     | NULL    |                |
+-------+------------------+------+-----+---------+----------------+


mysql> describe v_vendor_materials;
+-------+------------------+------+-----+---------+----------------+
| Field | Type             | Null | Key | Default | Extra          |
+-------+------------------+------+-----+---------+----------------+
| id    | int(10) unsigned | NO   | PRI | NULL    | auto_increment |
| vid   | int(10) unsigned | NO   | MUL | 0       |                |
| mid   | int(10) unsigned | NO   | MUL | 0       |                |
+-------+------------------+------+-----+---------+----------------+


mysql> describe v_vendor_countries;
+-------+------------------+------+-----+---------+----------------+
| Field | Type             | Null | Key | Default | Extra          |
+-------+------------------+------+-----+---------+----------------+
| id    | int(10) unsigned | NO   | PRI | NULL    | auto_increment |
| vid   | int(10) unsigned | NO   | MUL | 0       |                |
| mid   | int(10) unsigned | NO   | MUL | 0       |                |
+-------+------------------+------+-----+---------+----------------+






mysql> select * from v_country;
+----+----------+
| id | name     |
+----+----------+
|  1 | pakistan |
|  2 | India    |
|  3 | Iran     |
+----+----------+


mysql> select * from v_details;
+----+--------+------------------+---------------+-----------+
| id | vendor | email            | phone         | address   |
+----+--------+------------------+---------------+-----------+
|  1 | harris | harris@gmail.com | 0141 236 4523 | nowhere   |
|  2 | Boris  | boris@gmail.com  | 0141 451 7845 | somewhere |
|  3 | Doris  | doris@gmail.com  | 0141 353 7845 | anywhere  |
+----+--------+------------------+---------------+-----------+


mysql> select * from v_materials;
+----+---------+
| id | name    |
+----+---------+
|  1 | ceramic |
|  2 | iron    |
|  3 | plastic |
+----+---------+


mysql> select * from v_vendor_materials;
+----+-----+-----+
| id | vid | mid |
+----+-----+-----+
|  1 |   1 |   1 |
|  2 |   2 |   2 |
|  3 |   3 |   3 |
+----+-----+-----+


mysql> select * from v_vendor_countries;
+----+-----+-----+
| id | vid | mid |
+----+-----+-----+
|  1 |   1 |   1 |
|  2 |   2 |   2 |
|  3 |   3 |   3 |
+----+-----+-----+





mysql> select * from v_details d
          left outer join v_vendor_materials vm on vm.vid=d.id
          left outer join v_vendor_countries vc on vc.vid=d.id
          left outer join v_materials m on m.id=vm.id
          left outer join v_country c on c.id=vc.id;

+----+--------+------------------+---------------+-----------+------+------+------+------+------+------+------+---------+------+----------+
| id | vendor | email            | phone         | address   | id   | vid  | mid  | id   | vid  | mid  | id   | name    | id   | name     |
+----+--------+------------------+---------------+-----------+------+------+------+------+------+------+------+---------+------+----------+
|  1 | harris | harris@gmail.com | 0141 236 4523 | nowhere   |    1 |    1 |   1  |    1 |    1 |    1 |    1 | ceramic |    1 | pakistan |
|  2 | Boris  | boris@gmail.com  | 0141 451 7845 | somewhere |    2 |    2 |   2  |    2 |    2 |    2 |    2 | iron    |    2 | India    |
|  3 | Doris  | doris@gmail.com  | 0141 353 7845 | anywhere  |    3 |    3 |   3  |    3 |    3 |    3 |    3 | plastic |    3 | Iran     |
+----+--------+------------------+---------------+-----------+------+------+------+------+------+------+------+---------+------+----------+

如何从多个表中获取数据

1 个答案: