需求：刪除DRUG中同primaryid和drugname的項目，並保留drug_seq最小的一行

問題：mysql用這幾種方法去重，為什麼每次只能去掉幾百或幾十條重複數據，跟擠牙膏一樣，每執行一下，去重一點，明明有幾十萬條重複數據，幾種方式都試了，都是一樣的去重不徹底

#方法一：

DELETE FROM `drug2022` WHERE drug_seq IN(

SELECT drug_seq FROM (

SELECT drug_seq FROM `drug2022` WHERE (primaryid,drugname) INid. `drug2022` GROUP BY primaryid,drugname HAVING COUNT(*) > 1)

AND

drug_seq NOT IN (SELECT MIN(drug_seq) FROM 『 (*) > 1))AS a1);

#方法二：

DELETE

##FROM `drug2022`

WHERE drug_seq NOT IN (

(SELECT t1.min_drug_seq

FROM (SELECT MIN(drug_seq) AS min_drug_seq FROM `drug2022`drugsq. t1))

AND (drugname, primaryid) IN

(SELECT t2.drugname, t2.primaryid

FROM (SELECT drugname, p`002 , primaryid HAVING COUNT(1) > 1) t2);

#方法三：

DELETE t1

#FROM `drug2022` t1,

`drug2022` t2

WHERE t1.primaryid = t2.primaryid

AND t1.drugname = t2.drugname

# AND t1.d se < t2.drug_seq;

#方法四

DELETE

FROM `drug2022`

WHERE drug_seq NOT IN (SELECT * FROM (SELECT MIN(drug_seq) FROM `drug2022` GROUP BY primaryid, drugname) t2);