mysql 查询重复的数据的SQL优化方案

select from statiatalogue WHERE UPPER(Source) IN (SELECT UPPER(Source) FROM statiatalogue GROUP BY UPPER(Source) having count(UPPER(Source))>1) ORDER BY upper(Source) DESC;

CREATE TABLE statiatalogue_tmp SELECT UPPER(Source) AS Source FROM statiatalogue GROUP BY UPPER(Source) having count(UPPER(Source))>1;
ALTER TABLE statiatalogue_tmp add INDEX TX_1 (Source);
select s. from statiatalogue s WHERE UPPER(s.Source) IN (SELECT st.Source FROM statiatalogue_tmp st) ORDER BY UPPER(s.Source) DESC ;