SELECT sku_id,COUNT(id) FROM weight GROUP BY sku_id HAVING COUNT(sku_id) > 1 查詢重復數據里面每個最小的id
SELECT min(id) FROM weight GROUP BY sku_id HAVING COUNT(sku_id) > 1 查詢去掉重復數據最小id的其他數據
SELECT id,sku_id FROM weight WHERE sku_id IN( SELECT sku_id FROM weight GROUP BY sku_id HAVING COUNT(sku_id) > 1)AND id NOT IN( SELECT MIN(id) FROM weight GROUP BY sku_id HAVING COUNT(sku_id) > 1) 刪除去掉重復數據最小id的其他數據
DELETE FROM weight WHERE sku_id IN( SELECT sku_id FROM weight GROUP BY sku_id HAVING COUNT(sku_id) > 1)AND id NOT IN( SELECT MIN(id) FROM weight GROUP BY sku_id HAVING COUNT(sku_id) > 1) 原因是：刪除這個表的同時又查詢了這個表，查詢這個表的同時又去刪除了這個表，可以理解為死鎖。mysql不支持這種刪除查詢同一張表的操作
錯誤代碼： 1093You can't specify target table 'weight' for update in FROM clause 解決辦法如下：把要刪除的數據查詢出來做為一個第三方表，然后篩選刪除。
DELETE FROM `weight` WHERE sku_id IN( SELECT sku_id FROM (SELECT sku_id FROM `weight` GROUP BY sku_id HAVING COUNT(sku_id) > 1) table1)AND id NOT IN ( SELECT id FROM (SELECT MIN(id) AS id FROM `weight` GROUP BY sku_id HAVING COUNT(sku_id) > 1) table2) 更新也和上面操作原理相同。
