You'll be much better off doing this in Twig or PHP, as there is a lot of logic involved in fetching the content of live entries. But since you asked, here is an SQL query that joins 3 tables to get you the title of all live entries.
SELECT title FROM content
INNER JOIN entries ON entries.id = content.elementId
INNER JOIN elements ON elements.id = content.elementId
WHERE enabled = 1
AND draftId IS NULL AND revisionId IS NULL AND dateDeleted IS NULL
AND postDate <= now()
AND (expiryDate IS NULL OR expiryDate > now())
Some of the above logic was referenced from the EntryQuery class.