1、刪除子表數(shù)據(jù)（聯(lián)合查詢刪除）

delete?t1?

from?RR.tblOeWkPublicOrderItem?as?t1

inner?join?RR.tblOeWkPublicOrderHeader t2?on?t1.tran_code = t2.tran_code?and?t1.request_no = t2.request_no

where?create_date < @min_date;

2、聯(lián)合查詢修改

UPDATE T1 t1

JOIN T2 t2 ON t1.id = t2.id AND t1.no = t2.no

SET? t1.equipment_id = t2.equipment_id;

3、修改,1改成0，0改成1

UPDATE? tableName?

SET?STATUS?= CASE STATUS WHEN 0 THEN 1 WHEN 1 THEN 0 END?WHERE id='1';

4、查詢?nèi)掌?，七天前的年月日YYYY-MM-DD

SELECT?DATE(DATE_SUB(NOW(), INTERVAL 7 DAY));

5、修改表數(shù)據(jù)集

ALTER TABLE tableA CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;

6、創(chuàng)建索引

CREATE INDEX idx_id ON tblUser (user_id);

CREATE INDEX idx_url ON tblUser (url(255));

7、