Good. Now that you have updated your question a little, the answer is "yes, it can be done, but you do not have to do it like that."
First, just to show that this can be done:
SELECT u.* FROM users u
INNER JOIN skills s1 ON (u.id = s1.user_id AND s1.skill_name = 'php')
INNER JOIN skills s2 ON (u.id = s2.user_id AND s2.skill_name = 'html')
WHERE s1.skill_level = 2 AND s2.skill_level = 1 GROUP BY u.id;
I could not type a little text if you explained what you wanted in the beginning! :)
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