在 UNION 查询中结合 ORDER BY

Question

how do i combine ORDER BY in UNION query?

I tried this and got error:

SELECT country.country_name AS res
FROM   countries AS country
WHERE (lower (country.country_name) LIKE '%".$_POST['query']."%')
ORDER BY country.lang = '".$_POST['lang']."'
UNION
    SELECT  sec.loc AS res
    FROM    itin_secs AS sec
    WHERE   sec.loc LIKE '%".$_POST['query']."%'

Answer 1

I would recommend:

SELECT res
FROM (SELECT c.country_name as res, 1 as priority, c.lang
      FROM countries AS c
      WHERE lower(c.country_name) LIKE '%".$_POST['query']."%')
      UNION ALL  -- recommended instead of `UNION`
      SELECT  sec.loc Ares
      FROM itin_secs as sec, 2, NULL
      WHERE sec.loc LIKE '%".$_POST['query']."%'
    ) x
ORDER BY priority, lang = '".$_POST['lang']."';

This query is quite explicit about the final ordering. It also uses UNION ALL , so the query does not incur the overhead of removing duplicates.

As a secondary issue (I mean, the original query doesn't work), you should parameterize the query. You should really start by writing parameterized queries, so they are natural for anything you want to do.