PHP / MySQL关系表建议

Question

I was just wondering if I might get some advice on the following:

I'm building a site in CodeIgniter in which exists a content type "portfolio_item". The same portfolio item may be displayed in 3 places via checkbox controls: Homepage, Member Page and Client Page.

I'm just wondering what the best way to implement this relationship in the database is. I could have 3 relationship tables for each of the above scenarios, but to me this seems overkill (the site is quite small).

I was thinking of using one relationship table with the following fields:

type (homepage, client or member)
show_on_id
portfolio_id

The intent of the type field is to determine which table to retrieve the "show_on_id" from (either clients or member), if the type is homepage then show_on_id is not required.

Is there any obvious disadvantage of doing it this way?

Answer 1

Yes, there is a bit of a disadvantage. You could end up with multiple rows for the same setting, each might contradict each other. So, how you insert rows into this table, is very important.

If you will not add any more sections, might as well have the portfolio table:

CREATE TABLE `portfolio`
(`id` INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
`content` TEXT NULL,
`showHome` BOOLEAN NULL,
`showClient` BOOLEAN NULL,
`showMember` BOOLEAN NULL)

And then the table which links the users to their portfolios,

CREATE TABLE `portfolio_user`
(`id` INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
`portfolio` INT NOT NULL,
`user` INT NOT NULL)

If you are going to add more places where the portfolio can be displayed later, or if these places are dynamic, your method will work. I would just change 'type' to 'place' as that is easier to understand, then either use ENUM or another table to define the places that the portfolio can be shown.

Answer 2

Can there be one or many portfolio items for each location?

If many, use link tables, if only one use direct foreign key field to link to the portfolio.

I would advice against using one link table for all three based on personal experience with exactly such designs and the problems that can surface later.