How to Store Multiple Options selected by User in a Table

Question

So I want my users to be able to restrict who may contact them.

There are several factors they should be able to filter, including Age (e.g. Must be between 18 - 29), in

Answer 1

You can try with this:

criterium
------------
user_id type          value
1       AGE_MIN       18
1       AGE_MAX       29
1       INCOME_MIN    25000
1       INCOME_MAX    60000
1       DRUGS         Marijuana
1       DRUGS         Meth

Answer 2

No, don't store the values in CSV format in the database. Instead create a join table called user_drug and store one row for each user/drug combination:

user
id    name  income
1     Foo   10000
2     Bar   20000
3     Baz   30000

drug
id    name
1     Marijuana
2     Cocaine
3     Heroin

user_drug
user_id drug_id
1       1
1       2
2       1       
2       3
3       3

Answer 3

A DB column (at least theorethically) should NOT hold multiple values. Unfortunately, there are some programmers that store multiple values in a single column (values separated by comma for examples) - those programmers (in most cases) destroy the concept of DB and SQL.

I suggest you to read about Database Normalization to get a start in organizing your tables. And, do your best to achieve the Codd's Third Normal Form