Database SQL statement exercise "suggestions collection"

Hello everyone , I meet you again , I'm your friend, Quan Jun .

1、 Count the number of vehicles under the same house ：

SELECT houseid,COUNT(*) FROM t_car GROUP BY houseId;

2、 stay 1 On the basis of , Count the room number with the largest number of vehicles

SELECT houseId,COUNT(*) as car_num FROM t_car GROUP BY houseId ORDER BY car_num DESC LIMIT 1;

3、 Use one sql Batch addition of statements 3 strip t_car Record

INSERT INTO `t_car` VALUES (‘00111’, ‘ E AB1000’, ‘11111111111111111111111111111121’, ‘car_brand_01’, ‘car_color_01’, ‘car_type_01’, ‘2017-07-23 12:12:00’, ”), (‘00112’, ‘ E AC1234’, ‘11111111111111111111111111111122’, ‘car_brand_02’, ‘car_color_02’, ‘car_type_02’, ‘2018-07-12 12:12:00’, NULL), (‘00113’, ‘ E AD9999’, ‘11111111111111111111111111111123’, ‘car_brand_03’, ‘car_color_00’, ‘car_type_00’, ‘2018-07-12 12:12:00’, NULL);

4、 Delete payment on 2017 year 1 month 1 Payment records before day

DELETE FROM t_car_pay WHERE DATE(payTime)<‘2018-01-01’;

5、 Delete payment on 2017 year 1 month 1 Vehicle records before day

DELETE FROM t_car where carId in(SELECT carId from t_car_pay where DATE(payTime)<‘2018-01-01’);

DELETE c.*,p.* FROM t_car c , t_car_pay p WHERE (c.carid=p.carid ) AND DATE(p.payTime)<‘2018-01-01’; Delete multiple tables at the same time

6、 Use one according to the license plate number sql Statement batch modify the picture information of the vehicle

UPDATE t_car_image set path= ‘A-00benz.jpg’ WHERE carid in (select carid from t_car where carNumber=’ E AL0000′ )

7、 Check the latest payment records of all vehicles

select * from t_car_pay p where 1>(select COUNT(*) from t_car_pay where carId=p.carid and payTime>p.payTime) ORDER BY p.carId,p.payTime desc;

Reference resources ：

Before grouping N Record

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