html选择多项选择输入，将它们存储在mysql db中并搜索匹配项

Question

My question first and then (many...infos): what are my options thinking of usability and speed when i want a user to be able to select mulitple answers from a dropdownbox, save them on their profile, then let other users key in their searchcriteria (can be multiple again) and finally find users by those mutiple searchcriteria?

The infos: At the moment i am busy with a part of my website being a matchmaking system, much like datingsites use.

(I am using Mysqli, PHP and jQuery for my site)

I am using a dating site as an example to elaborate on my question: user A fills in his/her profile and enters their preference for a certain car brand: BMW, Volkswagen and Mercedes. User B wants to search the site for members who like BMW and/or Mercedes.

My original idea was to let user A fill in an input multiple html field and store it as an array (or comma-separated) in one column in my db. Then figure out how to select-search through that column which has stored arrays in it for user B.

So basically user A can enter multiple car brands in their profile and user B can give their criteria being also multiple car brands; the select query should fetch any row for matching criteria.

The input-field multiple looks like:

<tr><td>Which car brand(s) do you like?</td><td>
<select multiple name="CarBrandPref[]">
   <option  value="BMW"             > BMW</option>
   <option  value="Ford"            > Ford</option>
   <option  value="Mercedes"        > Mercedes </option>
   <option  value="GMC"             > GMC</option>
   <option  value="Volkswagen"      > Volkswagen </option>
   <option  value="Toyota"          > Toyota </option>
   <option  value="Audi"            > Audi </option>
</select>
</td></tr>

The profile table lay-out would be something like:

 Id     Name            CarbrandPref
--------------------------------------------------------
 1      Mike            bmw,volkswagen,mercedes
 2      Paul            Mercedes, ford, GMC
 3      Axel            GMC, ford, toyota, audi
 4      John            ford, bmw

User B would give searchcriteria 'bmw and mercedes'. The query should then return 3 rows:

Id     Name            CarbrandPref
---------------------------------------------------------
1      Mike            bmw,volkswagen,mercedes
2      Paul            Mercedes, ford, GMC
4      John            ford, bmw

Upon my searches on SO and other sites to get this working i noticed everyone saying that this (storing in arrays in db) was bad for performance etc. etc. Furthermore i can't get the select-search through the arrays in mysql to work.

So now i'm at a loss what to do. I don't want to add a column for each possble carbrand, but what to do else? Is there anyone who can help me with this? Any ideas are much appreciated!

I hope this is clear enough for someone to help me. If it is not, please tell me and i'll add the requested info.

I have used these links to be able to store the dropdownbox-populated arrays into the mysql database:

http://www.aleixcortadellas.com/main/2009/03/20/492/

http://toolspot.org/how-to-store-array-mysql.php

Answer 1

You have three choices.

The first is to go down the path you are one and try to compare two comma delimited lists. This produces really, really ugly SQL. It does not allow indexes. The basic idea is something like:

where find_in_set(substring_index(@list, ',', 1), CarBrands) > 0 or
      find_in_set(substring_index(substring_index(@list, ',', 2), ',', -1), CarBrands) > 0 or
      . . .

The second is to introduce a new table, which has one row for a user and a favorite whatever. Let's make this general, so there is a column for the user, a column for category ("CarBrand") and a name. Then the query looks something like:

from Profile p left outer join
     Favorites f
     on p.userId = f.userId and f.Category = 'CarBrand'
group by p.userId
having sum(f.Name = 'Mercedes') > 0 and
       sum(f.Name = 'BMW') > 0;

The third option is to use full text search and the match function. The documentation is here .

My guess is that a full text index is probably the easiest way for you to do what you want.

EDIT:

The query about full text index versus option 2. Probably the key question has to do with stop words and short terms. The full text index, for instance, drops words with less than 4 characters (by default, you can change both of these). It also has a list of stop words.

My personal inclination would be to use the second option. But the reasons may not be good ones. It uses standard SQL and I'm comfortable with the data structures and queries. So, it gives me more control over the results.

In your case, the full text search is probably easier to implement quickly and would very likely be as fast or faster. The full text search also lets you do more complex booleans, such as mixing "AND" and "OR" and doing natural language search to get a relevance value.

Answer 2

You should use a third table to map between users and car marques. The table will have a primary key covering two columns, each of which is a foreign key to one of the other two tables. The presence of a row in this table mapping between "Bastian" and "BMW" means that he has chosen that marque. Absence of such a row means no association exists.

More specifically, table 1 has users, table 2 has car brands. each of those have a primary key column with an id #. The third table links these two. See Many-to-Many Relationships in MySQL and here and here