你能否告诉我这两句话哪一句更快?mysql - “INNER JOIN”或“IN”。哪个更快?
第一句:
SELECT DISTINCT(t1.user_id) FROM table_users as t1 WHERE t1.user_town IN (SELECT t2.town FROM table_towns as t2)
第二个句子:
SELECT DISTINCT(t1.user_id) FROM table_users as t1
INNER JOIN (SELECT t2.town FROM table_towns as t2) as t3 ON t1.user_town = t3.town
我使用的选择通常是复杂一点。 而且,如果可能,我尝试使用IN(...),因为我可以传递值或表格选择。
我已经将SELECT t1。*的结果更改为SELECT DISTINCT(t1.user_id)以避免不同的结果。因为它通常是我真正关心的 – Seeker