已有數據的表-建聯合索引

清理重複數據，創建聯合惟一索引

1. 查看重複數據

SELECT * FROM holiday_focamobilerel 
WHERE (cardnumber, mobile) IN (SELECT cardnumber, mobile FROM holiday_focamobilerel GROUP BY cardnumber, mobile HAVING COUNT(1) > 1);

2. 刪除重複數據

- 保留order_id and sub_order_id不爲空的

- 若是order_id和sub_order_id都爲空，保留id最大的

DELETE FROM holiday_focamobilerel h
WHERE (cardnumber, mobile) IN (SELECT cardnumber, mobile FROM holiday_focamobilerel GROUP BY cardnumber, mobile HAVING COUNT(1) > 1)
AND h.id NOT IN (select id from holiday_focamobilerel h where h.order_id  is not null  or h.sub_order_id  is not null )
and h.id not in (SELECT MAX(id) FROM holiday_focamobilerel GROUP BY cardnumber, mobile HAVING COUNT(1) > 1);

 3. 創建聯合惟一約束

alter table holiday_focamobilerel add constraint cardnumber_mobile_key unique("cardnumber","mobile")