Question

I have a simple php web app. I need to add an option for users to hide certain details from their public profiles. The database is something like:

id     username    phone      email 
1      foo1        888-888    [e-mail]
2      foo2        999-999    [e-mail]
3      foo3        111-111    [e-mail]

Now I have 2 options. First is to have another table and use id as the foreign key for referencing. Like

fkeyID     disp_phone      disp_email 
1          0               0
2          0               1
3          1               1

Where 1 is true and 0 is false. Then use SQL join on 2 tables to find whether they want to display their phone/email or not.

2nd Option is: to prefix some flag value like $ in case user wants to forbid public view. Then use a simple php check before displaying or saving preferences. Like:

id     username    phone      email 
1      foo1        $888-888   $[e-mail]
2      foo2        $999-999   [e-mail]
3      foo3        111-111    [e-mail]

Please tell which is the better option in terms of space and complexity and why.

Answer 1

Given that id and fKeyID are both primary keys an SQL JOIN will be very efficient in the first solution.

IMO the first solution is superior to the second since you can perform SELECT s based on visibility settings in an efficient way (i.e., select only users whose phone numbers are public without considering substrings, e.g., ... WHERE LEFT(phone, 1) != '$' etc.).

(This advantage may have no relevance in your case, however.)

---

And then there was this third possibility:

id | username | phone   | phone_disp | email    | email_disp
------------------------------------------------------------
1  | foo1     | 888-888 | 0          | [e-mail] | 0
2  | foo2     | 999-999 | 0          | [e-mail] | 1
3  | foo3     | 111-111 | 1          | [e-mail] | 1

This will keep data and visibility settings together. It is otherwise identical to the first solution, except you don’t need to JOIN.