Storing users data efficiently in mysql database

Question

I am developing a recommendation engine, so that requires storing lots of data and keeping track of every move made by the user. So, basically my website is a product search engine and will be having sets of queries as users data. Following are some examples of the data set

Example

User1 :
1. Apple Ipod tOuch
2. Samsung Galaxy Ace Plus
3. HArry Porter 

User2 :
1. Product1
2. Product2

and so on.

One way(naive) could be having an ID associated with each of my users and then having a string corresponding to that ID which will be of this form(strings separated with ~) :-

Unique ID - Apple IPod TOuch~Samsung Galaxy Ace Plus~HArry Porter 

But this method won't be efficient considering how I would be playing with those data later on.

Can any one come up with a very efficient model fairly easily implementable in mysql ?

Comment if I am unclear in asking my doubt.

Answer 1

The classic design is a table for users :

Users(user_id,user_name,reg_date....)

table for products :

Products(prod_id,prod_name,prod_cost....)

table with mapping user-->products :

User_products(user_id,prod_id ....)

Example :

Users :

user_id|user_name
1200   | User1 
7856   | User2

Products :

prod_id | prod_name
12900   | Apple Ipod tOuch
45673   | Samsung Galaxy Ace Plus
99876   | HArry Porter 
34590   | Product1
56283   | Product2

User_products :

user_id | prod_id
1200    |12900
1200    |45673
1200    |99876
7856    |34590
7856    |56283