如何设计这个MySQL结构？

Question

Ok so here is my problem.

I have a selection of items, their names are;

UAT-1 UAT-2 UAT-3

Each item has 'sections', however not every item has the same sections as the previous. For example, UAT-1 will have the sections - 'Red', 'Green', 'Blue'.

UAT-2 will have the seconds - 'Red', 'Brown', 'Purple'

UAT-3 will ahve the sections - 'Gold', 'Silver', 'Red'

What is the best way to design MySQL table(s) for this problem? I was thinking something along the lines of;

items

+-----+-----------+
|id   |item_name  |
|-----|-----------|
|1    |UAT-1      |
|2    |UAT-2      |
+-----+-----------+

sections

+-------------------------------+
|id   |section_name |belongs_to |
|-----|-------------|-----------|
|1    |Red          |1          |
|2    |Green        |1          |
|3    |Blue         |2          |
|4    |Purple       |1          |
|     |             |           |
|     |             |           |
+-------------------------------+

However how would I deal with a case where a two sections belong to one item?

Thanks!

Answer 1

One approach would be to add an intermediate table. This lets your "items" and "sections" live as distinct records.

Items:

+-----+-----------+
|id   |item_name  |
|-----|-----------|
|1    |UAT-1      |
|2    |UAT-2      |
+-----+-----------+

Sections:

+--------------------+
|id   |section_name  |
|-----|--------------|
|1    |Red           |
|2    |Green         |
|3    |Blue          |
|4    |Purple        |
+--------------------+

ItemsSections:

+---------------+
|item  |section |
|---------------|
|1     |1       |
|1     |2       |
|1     |4       |
|2     |3       |
+---------------+

You would get the sections for a specific item with a query like:

SELECT
    Sections.*
FROM
    Sections
    RIGHT JOIN ItemsSections
        ON Sections.id = ItemsSections.Section
WHERE
    ItemsSections.item = 1

Answer 2

For an n:m relation you would usually have two base tables and one relation table:

items
+-----+-----------+
|id   |item_name  |
|-----|-----------|
|1    |UAT-1      |
|2    |UAT-2      |
|3    |UAT-3      |
+-----+-----------+

sections
+-------------------+
|id   |section_name |
|-----|-------------|
|1    |Red          |
|2    |Green        |
|3    |Blue         |
|4    |Brown        |
|5    |Purple       |
|6    |Gold         |
|7    |Silver       |
+-------------------

item_sections
+--------------------+
|id_item |id_section |
|--------|-----------|
|1       |1          |
|1       |2          |
|1       |3          |
|2       |1          |
|2       |4          |
|2       |5          |
|3       |1          |
|3       |6          |
|3       |7          |
+--------------------+

Answer 3

UAT-1 will have the sections - 'Red', 'Green', 'Blue'.

UAT-2 will have the seconds - 'Red', 'Brown', 'Purple'

UAT-3 will ahve the sections - 'Gold', 'Silver', 'Red'

+-----+-----------+  +-----+--------------+
|id   |item_name  |  |id   |section_name  |
|-----|-----------|  |-----|--------------|
|1    |UAT-1      |  |1    |Red           |
|2    |UAT-2      |  |2    |Green         |
|3    |UAT-3      |  |3    |Blue          |
+-----+-----------+  |4    |Brown         |
                     |5    |Purple        |
                     |6    |Gold          |
                     |7    |Silver        |
                     +-----+--------------+

+-------------------------------+
|id   |section_id   |item_id    |
|-----|-------------|-----------|
|1    |1            |1          |
|2    |2            |1          |
|3    |3            |1          |
|4    |1            |2          |
|5    |4            |2          |
|6    |5            |2          |
|7    |6            |3          |
|8    |7            |3          |
|9    |1            |3          |
+-------------------------------+