how to order by relevance when using cases PDO Full Text Search

Question

I have a query with a few cases in:

$search = $_GET['search'];


$array = $pdo->prepare("SELECT * , CASE 
     WHEN CHAR_LENGTH(index.product_description) > 32 THEN CONCAT(SUBSTRING(index.product_description, 1, 32), '...') ELSE index.product_description
   END AS product_description, `product_title`, CASE 
     WHEN CHAR_LENGTH(index.product_title) > 18 THEN CONCAT(SUBSTRING(index.product_title, 1, 18), '...')
     ELSE index.product_title
   END AS product_title from `index` where MATCH (`product_title`) AGAINST (:search IN BOOLEAN MODE) and `category_name` = 'category1' LIMIT :start, :limit");
$array->execute(array(':search' => $search, ':start' => $start, ':limit' => $limit));

I want to add order by relevance, I have this working separately without using cases:

$search = $_GET['search'];
$search2 = $_GET['search'];


$array = $pdo->prepare("SELECT * , MATCH (`product_title`) AGAINST (:search2 IN BOOLEAN MODE) AS relevance 
FROM `index` where MATCH (`product_title`) AGAINST (:search IN BOOLEAN MODE) and `category_name` = 'category1' order by relevance DESC LIMIT :start, :limit");
$array->execute(array(':search' => $search, ':search2' => $search2, ':start' => $start, ':limit' => $limit));

I have tried adding the:

SELECT * , MATCH (`product_title`) AGAINST (:search2 IN BOOLEAN MODE) AS relevance 
FROM `index`

before and after the cases and it doesnt seem to work.

Where in the first query would I add the order by relevance or how should it be structured when using cases?

Thanks

Answer 1

You need an order by clause to order by relevance. You can put the MATCH statement directly in the order by:

SELECT index.*,
       (CASE WHEN CHAR_LENGTH(index.product_description) > 32
             THEN CONCAT(SUBSTRING(index.product_description, 1, 32), '...')
             ELSE index.product_description
        END) AS product_description, `product_title`,
       (CASE WHEN CHAR_LENGTH(index.product_title) > 18
             THEN CONCAT(SUBSTRING(index.product_title, 1, 18), '...')
             ELSE index.product_title
        END) AS product_title
from `index`
where MATCH (`product_title`) AGAINST (:search IN BOOLEAN MODE) and `category_name` = 'category1'
order by MATCH (`product_title`) AGAINST (:search IN BOOLEAN MODE) desc
LIMIT :start, :limit;