Question

Is it possible to achieve this task with a single MySQL query?

Table urls. Fields {id, url}

1, http://www.mysite.kom
2, mysite.kom

3, anothersite.kom

Table logs. Fields {id, url_id, group_type – a number in the range of 1..10}

1, 1, 4
2, 1, 4
3, 2, 5
4, 2, 5

5, 3, 9

The result of the query in this example should be: 1 (mysite.com and http://www.mysite.com = 1)

THE GOAL:

Need to count all distinct urls recorded in logs table, but with a few conditions:

1) Urls with and without www. prefix, like mysite.kom and http://www.mysite.kom,
should be counted as 1 (not 2).

2) Have group_type in the range of 4..6

3) Now, any of these urls with group_type 4..6, which appear in the list of those with group_type lower than 4 – should be ignored and not counted at all.

The SQL code:

SELECT COUNT(DISTINCT TRIM(LEADING 'www.' FROM b.url))
FROM logs a
INNER JOIN urls b
ON a.url_id = b.id
WHERE (group_type BETWEEN 4 AND 6) 

----- and this condition below -----

AND TRIM(LEADING 'www.' FROM b.url)
NOT IN (
  SELECT TRIM(LEADING 'www.' FROM b.url)
  FROM logs a
  INNER JOIN urls b
  ON a.url_id = b.id
  WHERE (group_type < 4)
)

If my sql query is correct, can it be optimized (to look more compact)?

Answer 1

Here’s one way:

SELECT trimmed_url
  FROM ( SELECT TRIM(LEADING 'www.' FROM urls.url) AS trimmed_url,
                MIN(logs.group_type) AS min_group_type
           FROM logs
           JOIN urls
             ON urls.id = logs.url_id
          GROUP
             BY trimmed_url
       ) t
 WHERE min_group_type BETWEEN 4 AND 6
;

But only you can judge whether it looks more compact to you, and only testing can determine whether it performs better.