Mysql 使用sql刪除同表中重復數據並加唯一索引

同一張表中，假設以兩個字段做唯一業務,這兩個字段分別為key1，key2,

則以這兩個字段為唯一

DELETE tablename FROM
    tablename ,
    (
        SELECT
            min(id) id,
           key1, key2
        FROM
            tablename 
        GROUP BY
            
            key1, key2
        HAVING
            count(*) > 1
    ) t2
		WHERE
 tablename .key1=t2.key1 
AND tablename .key2=t2.key2
AND tablename .id > t2.id;

　增加唯一索引

ALTER TABLE t_procurement_order_instock add unique index uniq_t_procurement_order_instock(`t_procurement_order_instock_id`);  

ALTER TABLE tablename 
DROP INDEX ix_instock_date_warehouse_g_f_lu_standard_item,
ADD INDEX idx_f_lu_standard_item_warehouse_g_item_status_instock_date(`f_lu_standard_item`,`warehouse_g`,`item_status`,`instock_date`);


ALTER TABLE tablename 
DROP INDEX IND_PAY_ORDER_1;                                                                     
ALTER IGNORE TABLE PAY_ORDER ADD UNIQUE INDEX IND_PAY_ORDER_1(ORDER_ID);               將ORDER_ID設為唯一索引（IND_PAY_ORDER_1）刪除重復數據