how to fetch data from multiple tables

Question

So I normalize my database and it seems quite complicated for me to fetch or update records in tables. I have 5 tables ( details , country , materials , vendor_countries , vendor_materials ). Actually "details" is my main table.

• country table have two column ( id , name ).
• materials table also have two column( id , name ).
• details table have personnel information about vendors ( name , email , phone , address ).

A vendor could have multiple countries and materials so I made two more tables vendor_countries and vendor_materials and their column are ( did , cid ), ( did , mid ). "did" is the id of each vendor coming from details table and cid , mid is the country id and material id coming from country and material table.

Now I want to fetch vendors along with their countries and materials.

here is my details table, vendor_countries and vendor_materials tables

so far I made a query which is shown below:

select dt.vendor,
       dt.email,
       dt.address,
       c.country,
       m.material,
       c.country
  from country c
       inner join vendor_countries vc on (c.id = vc.cid)
       right join details dt on (dt.id = vc.did)
       left join vendor_materials vm on dt.id = vm.did
       left join material m on vm.mid = m.id

and i am getting results like this:

which is not right it should be in 3 rows because "ali" vendor works in 3 countries and 3 materials. I am looking for some smart solution which also not slow down my page. Thanks in advance.

Answer 1

In the absence of any response regarding table schema I tried to re-create the tables based upon the descriptions above -prefixing each table with v_ so I could group the tables in this db and referencing did as vid ( vendor id ) and populating with what I believed to be the sample data from the question

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     |
+----+--------+------------------+---------------+-----------+------+------+------+------+------+------+------+---------+------+----------+

or, a more selective query

select 
    d.`id` as `vid`,
    d.`vendor`,
    d.`email`,
    d.`phone`,
    d.`address`,
    m.`name` as `material`,
    c.`name` as `country`
    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;


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