How to check if a row of the first column is similar to the second?

Question

I use the query

Select t1.name as first, t2.name as second From products t1, products t2

that creates two columns like below. (A,B are for explaining purposes)

Before the query

-name-
A
B
C
D
E

After the query

-first- -second-
A        A
B        A
C        A
D        A
E        A
A        B
B        B
C        B
D        B
E        B

How to check if a row of the first column is similar to the second ?

UPDATE

I run mySQL

With similar, I mean like to find their similarity percentage are more of a specified value. Like if the first contains this is a string and second i wear a string there is a percentage of similarity. If this % is more than 70 then they are similar.

Answer 1

there are many ways, here is one that will give you all the products that match your criteria (first = second)

SELECT
  t1.name AS first, t2.name AS second 
FROM
  products t1, products t2
WHERE
  t1.name = t2.name

or, if you need all the values

Select
  t1.name as first t2.name as second, (if t1.name = t2.name THEN 1 ELSE 0) as match
From 
  products t1, products t2

Answer 2

OK, here's what to do.

1. run the select script like you do to get all possible combinations you want to calculate.
2. make a php script that loops through each of these and calculates the percentage of similarity by using similar_text function in php (http://www.php.net/manual/en/function.similar-text.php)
3. write all three values to a new table
4. now just query the new table getting all rows where the percent is greater than 70.