How to display most related content according to given keywords in a product area?

Question

I am creating a product area.All of the products have some keyword ids in it.What i am going to implement is if a product was selected, i want to display most related other products beneath the page. As for example data,

product_id | product_name | keywords

23     | product1     | 2,4,13
31     | product3     | 2,4,8
10     | product6     | 2,4
11     | product4     | 2,3
34     | product2     | 2,4
54     | product5     | 2,7
12     | product8     | 4,8

Lets say I have to display related products for product contains keyword 2 and 4. Currently I am using following to get the related products

$sql="SELECT * FROM table1 WHERE keywords REGEXP '(^|,)2(,|$)' OR keywords REGEXP '(^|,)4(,|$)' ORDER BY product_id"

But sometimes this will not return mostly related products.

As for the above example data, product_id 23,31,10,34 should take higher precedence rather than other records.

Can that be possible? Then what should i do to overcome this? thanks for all replies.

Answer 1

Just use FIND_IN_SET

SQLFiddle demo

select t.*,
SIGN(FIND_IN_SET('2',keywords))+SIGN(FIND_IN_SET('4',keywords))
as FindWeight
from t
where 
SIGN(FIND_IN_SET('2',keywords))+SIGN(FIND_IN_SET('4',keywords))>0
ORDER BY FindWeight DESC

Answer 2

leftclickben is right about how you should have structured your tables.

However if you want to continue with this, then the following would work

keywords LIKE '2,%' OR keyword LIKE '%,2,%' OR keyword LIKE '%,4,%' OR keyword LIKE '%,4,%'

Careful - be very consistent about the placement of commas and spaces.