Select only one term_id from taxonomy - mysql

Question

I have a custom post type and a taxonomy, where I can put more the one value to the taxonomy, in this case the taxonomy is the city. I want to make a query that the result is the posts that only have ONE value set. Example: I want all posts that the taxnomy is only "term_id = 3" that is "sao-paulo-sp".
But I have some posts that has more than one value set to it, like "sao-paulo-sp, city 2, city 3 city 4, etc" and this kinda of post keep showing up in my results.
SELECT wp.ID, wp.post_title, wt.term_id FROM wp_posts wp
INNER JOIN wp_term_relationships wtr ON (wp.`ID` = wtr.`object_id`)
INNER JOIN wp_term_taxonomy wtt ON (wtr.`term_taxonomy_id` =
wtt.`term_taxonomy_id`)
INNER JOIN wp_terms wt ON (wt.`term_id` = wtt.`term_id`)
WHERE wtt.taxonomy = 'cities'
AND wt.slug = 'sao-paulo-sp'
ORDER BY wp.ID
I would like that the result was the posts that only have "sao-paulo-sp" or "term_id = 3' as his value to the taxonomy cities

Answer 1

If I understand correctly, you want something like this:
SELECT wp.ID, wp.post_title, wt.term_id
FROM wp_posts wp INNER JOIN
wp_term_relationships wtr
ON wp.`ID` = wtr.`object_id` INNER JOIN
wp_term_taxonomy wtt
ON wtr.`term_taxonomy_id` = wtt.`term_taxonomy_id` INNER JOIN
wp_terms wt
ON wt.`term_id` = wtt.`term_id`
WHERE wtt.taxonomy = 'cities'
GROUP BY wp.ID
HAVING COUNT(*) = 1 AND MAX(wt.slug) = 'sao-paulo-sp'
ORDER BY wp.ID;
I am not sure what wt.term_id is doing in the SELECT list.

Answer 2

Srry, my english was not good enough to specify my question, if help anyone I solved my problem doing a NOT IN in a select that has term_id different than tem_id 3.
SELECT wp.ID, wp.post_title, wt.slug
FROM wp_posts wp
INNER JOIN wp_term_relationships wtr ON wp.`ID` = wtr.`object_id`
INNER JOIN wp_term_taxonomy wtt ON wtr.`term_taxonomy_id` =
wtt.`term_taxonomy_id`
INNER JOIN wp_terms wt ON wt.`term_id` = wtt.`term_id`
WHERE wtt.taxonomy = 'cidades'
AND wp.ID NOT IN
(SELECT wp.ID
FROM wp_posts wp
INNER JOIN wp_term_relationships wtr ON wp.`ID` = wtr.`object_id`
INNER JOIN wp_term_taxonomy wtt ON wtr.`term_taxonomy_id` =
wtt.`term_taxonomy_id`
WHERE wtt.taxonomy ='cidades' and wtt.term_id <> 3)
ORDER BY wp.ID