Question

Is there anyway to optimize the following query:

SELECT
  t1.id,
  (SELECT SUM(col1) FROM table_name_two t2 WHERE t2.name LIKE CONCAT('%',t1.name)) AS col1_count
FROM
  table_name_one t1
ORDER BY 
  col1_count DESC

Using ORDER BY col1_count DESC takes a long time.

Thanks.

Answer 1

Just make a normal join with your comparison in the join’s on clause:

SELECT
  t1.id,
  SUM(t2.col1) AS col1_count
FROM table_name_one t1
LEFT JOIN table_name_two t2 on t2.name LIKE CONCAT('%', t1.name)
GROUP BY 1
ORDER BY 2 DESC

It should be way faster this way – it’s basically one query instead of “n” queries, although it won’t get any help from indexes using the LIKE operator with a leading %