插入记录
SQL110 插入记录(一)
描述
牛客后台会记录每个用户的试卷作答记录到exam_record表,现在有两个用户的作答记录详情如下:
用户1001在2021年9月1日晚上10点11分12秒开始作答试卷9001,并在50分钟后提交,得了90分;
用户1002在2021年9月4日上午7点1分2秒开始作答试卷9002,并在10分钟后退出了平台。
试卷作答记录表exam_record中,表已建好,其结构如下,请用一条语句将这两条记录插入表中。
该题最后会通过执行SELECT uid, exam_id, start_time, submit_time, score FROM exam_record;来对比结果
示例1
输入:
drop table if EXISTS exam_record;
CREATE TABLE IF NOT EXISTS exam_record (
id int PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
uid int NOT NULL COMMENT '用户ID',
exam_id int NOT NULL COMMENT '试卷ID',
start_time datetime NOT NULL COMMENT '开始时间',
submit_time datetime COMMENT '提交时间',
score tinyint COMMENT '得分'
)CHARACTER SET utf8 COLLATE utf8_general_ci;
TRUNCATE exam_record;
复制
输出:
1001|9001|2021-09-01 22:11:12|2021-09-01 23:01:12|90
1002|9002|2021-09-04 07:01:02|None|None
答案:
INSERT INTO exam_record(uid, exam_id, start_time, submit_time, score)
VALUES(1001, 9001, '2021-09-01 22:11:12', '2021-09-01 23:01:12', 90),
(1002, 9002, '2021-09-04 07:01:02', null, null);
SQL111 插入记录(二)
描述
现有一张试卷作答记录表exam_record,结构如下表,其中包含多年来的用户作答试卷记录,由于数据越来越多,维护难度越来越大,需要对数据表内容做精简,历史数据做备份。
表exam_record:
我们已经创建了一张新表exam_record_before_2021用来备份2021年之前的试题作答记录,结构和exam_record表一致,请将2021年之前的已完成了的试题作答纪录导入到该表。
后台会通过执行"SELECT * FROM exam_record_before_2021;"语句来对比结果
示例1
输入:
drop table if EXISTS exam_record;
CREATE TABLE IF NOT EXISTS exam_record (
id int PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
uid int NOT NULL COMMENT '用户ID',
exam_id int NOT NULL COMMENT '试卷ID',
start_time datetime NOT NULL COMMENT '开始时间',
submit_time datetime COMMENT '提交时间',
score tinyint COMMENT '得分'
)CHARACTER SET utf8 COLLATE utf8_general_ci;
CREATE TABLE IF NOT EXISTS exam_record_before_2021 (
id int PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
uid int NOT NULL COMMENT '用户ID',
exam_id int NOT NULL COMMENT '试卷ID',
start_time datetime NOT NULL COMMENT '开始时间',
submit_time datetime COMMENT '提交时间',
score tinyint COMMENT '得分'
)CHARACTER SET utf8 COLLATE utf8_general_ci;
TRUNCATE exam_record;
TRUNCATE exam_record_before_2021;
INSERT INTO exam_record(uid,exam_id,start_time,submit_time,score) VALUES
(1001, 9001, '2020-01-01 09:00:01', null, null),
(1001, 9002, '2020-01-02 09:01:01', '2020-01-02 09:21:01', 70),
(1001, 9002, '2020-09-02 09:00:01', null, null),
(1002, 9001, '2021-05-02 10:01:01', '2021-05-02 10:30:01', 81),
(1002, 9002, '2021-09-02 12:01:01', null, null);
复制
输出:
1|1001|9002|2020-01-02 09:01:01|2020-01-02 09:21:01|70
答案:
INSERT INTO exam_record_before_2021(uid, exam_id, start_time, submit_time, score)
SELECT uid, exam_id, start_time, submit_time, score
FROM exam_record
WHERE YEAR(start_time) < '2021' AND submit_time IS NOT NULL
SQL112 插入记录(三)
描述
现在有一套ID为9003的高难度SQL试卷,时长为一个半小时,请你将 2021-01-01 00:00:00 作为发布时间插入到试题信息表examination_info(其表结构如下图),不管该ID试卷是否存在,都要插入成功,请尝试插入它。
试题信息表examination_info:
后台会通过执行 SELECT exam_id,tag,difficulty,duration,release_time FROM examination_info 语句来对比结果。
示例1
输入:
drop table if EXISTS examination_info;
CREATE TABLE IF NOT EXISTS examination_info (
id int PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
exam_id int UNIQUE NOT NULL COMMENT '试卷ID',
tag varchar(32) COMMENT '类别标签',
difficulty varchar(8) COMMENT '难度',
duration int NOT NULL COMMENT '时长(分钟数)',
release_time datetime COMMENT '发布时间'
)CHARACTER SET utf8 COLLATE utf8_bin;
TRUNCATE examination_info;
INSERT INTO examination_info(exam_id,tag,difficulty,duration,release_time) VALUES
(9001, 'SQL', 'hard', 60, '2020-01-01 10:00:00'),
(9002, '算法', 'easy', 60, '2020-01-01 10:00:00'),
(9003, 'SQL', 'medium', 60, '2020-01-02 10:00:00'),
(9004, '算法', 'hard', 80, '2020-01-01 10:00:00');
复制
输出:
9001|SQL|hard|60|2020-01-01 10:00:00
9002|算法|easy|60|2020-01-01 10:00:00
9004|算法|hard|80|2020-01-01 10:00:00
9003|SQL|hard|90|2021-01-01 00:00:00
答案:
DELETE FROM examination_info
WHERE exam_id=9003;
INSERT INTO examination_info
VALUES(NULL,9003, 'SQL','hard', 90, '2021-01-01 00:00:00')
更新记录
SQL113 更新记录(一)
描述
现有一张试卷信息表examination_info,表结构如下图所示:
请把examination_info表中tag为PYTHON的tag字段全部修改为Python。
后台会通过执行'SELECT exam_id,tag,difficulty,duration,release_time FROM examination_info;'语句来对比结果。
示例1
输入:
drop table if EXISTS examination_info;
CREATE TABLE IF NOT EXISTS examination_info (
id int PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
exam_id int UNIQUE NOT NULL COMMENT '试卷ID',
tag varchar(32) COMMENT '类别标签',
difficulty varchar(8) COMMENT '难度',
duration int NOT NULL COMMENT '时长',
release_time datetime COMMENT '发布时间'
)CHARACTER SET utf8 COLLATE utf8_bin;
TRUNCATE examination_info;
INSERT INTO examination_info(exam_id,tag,difficulty,duration,release_time) VALUES
(9001, 'SQL', 'hard', 60, '2020-01-01 10:00:00'),
(9002, 'python', 'easy', 60, '2020-01-01 10:00:00'),
(9003, 'Python', 'medium', 80, '2020-01-01 10:00:00'),
(9004, 'PYTHON', 'hard', 80, '2020-01-01 10:00:00');
复制
输出:
9001|SQL|hard|60|2020-01-01 10:00:00
9002|python|easy|60|2020-01-01 10:00:00
9003|Python|medium|80|2020-01-01 10:00:00
9004|Python|hard|80|2020-01-01 10:00:00
答案:
UPDATE examination_info
SET tag = 'Python'
WHERE tag = 'PYTHON'
SQL114 更新记录(二)
描述
现有一张试卷作答记录表exam_record,其中包含多年来的用户作答试卷记录,结构如下表:
作答记录表exam_record:
submit_time为 完成时间
请把exam_record表中2021年9月1日之前开始作答的未完成记录全部改为被动完成,即:将完成时间改为'2099-01-01 00:00:00',分数改为0。
示例1
输入:
drop table if EXISTS exam_record;
CREATE TABLE IF NOT EXISTS exam_record (
id int PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
uid int NOT NULL COMMENT '用户ID',
exam_id int NOT NULL COMMENT '试卷ID',
start_time datetime NOT NULL COMMENT '开始时间',
submit_time datetime COMMENT '提交时间',
score tinyint COMMENT '得分'
)CHARACTER SET utf8 COLLATE utf8_general_ci;
INSERT INTO exam_record(uid,exam_id,start_time,submit_time,score) VALUES
(1001, 9001, '2020-01-02 09:01:01', '2020-01-02 09:21:01', 80),
(1001, 9002, '2021-09-01 09:01:01', '2021-09-01 09:21:01', 90),
(1002, 9001, '2021-08-02 19:01:01', null, null),
(1002, 9002, '2021-09-05 19:01:01', '2021-09-05 19:40:01', 89),
(1003, 9001, '2021-09-02 12:01:01', null, null),
(1003, 9002, '2021-09-01 12:01:01', null, null);
复制
输出:
1001|9001|2020-01-02 09:01:01|2020-01-02 09:21:01|80
1001|9002|2021-09-01 09:01:01|2021-09-01 09:21:01|90
1002|9001|2021-08-02 19:01:01|2099-01-01 00:00:00|0
1002|9002|2021-09-05 19:01:01|2021-09-05 19:40:01|89
1003|9001|2021-09-02 12:01:01|None|None
1003|9002|2021-09-01 12:01:01|None|None
答案:
UPDATE exam_record
SET submit_time = '2099-01-01 00:00:00', score = 0
WHERE date(start_time) < date('2021-09-01 00:00:00') AND score IS NULL
删除记录
SQL115 删除记录(一)
描述
现有一张试卷作答记录表exam_record,其中包含多年来的用户作答试卷记录,结构如下表:
作答记录表exam_record:
start_time是试卷开始时间
submit_time 是交卷,即结束时间
请删除exam_record表中作答时间小于5分钟整且分数不及格(及格线为60分)的记录;
后台会执行您的SQL,然后通过 SELECT * FROM exam_record; 语句来筛选出剩下的数据,与正确数据进行对比。
示例1
输入:
drop table if EXISTS exam_record;
CREATE TABLE IF NOT EXISTS exam_record (
id int PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
uid int NOT NULL COMMENT '用户ID',
exam_id int NOT NULL COMMENT '试卷ID',
start_time datetime NOT NULL COMMENT '开始时间',
submit_time datetime COMMENT '提交时间',
score tinyint COMMENT '得分'
)CHARACTER SET utf8 COLLATE utf8_general_ci;
TRUNCATE exam_record;
INSERT INTO exam_record(uid, exam_id, start_time, submit_time, score) VALUES
(1001, 9001, '2020-01-01 22:11:12', '2020-01-01 23:16:12', 50),
(1001, 9002, '2020-01-02 09:01:01', '2020-01-02 09:06:00', 58),
(1002, 9001, '2021-05-02 10:01:01', '2021-05-02 10:05:58', 60),
(1002, 9002, '2021-06-02 19:01:01', '2021-06-02 19:05:01', 54),
(1003, 9001, '2021-09-05 19:01:01', '2021-09-05 19:40:01', 49),
(1003, 9001, '2021-09-05 19:01:01', '2021-09-05 19:15:01', 70),
(1003, 9001, '2021-09-06 19:01:01', '2021-09-06 19:05:01', 80),
(1003, 9002, '2021-09-09 07:01:02', null, null);
复制
输出:
1|1001|9001|2020-01-01 22:11:12|2020-01-01 23:16:12|50
3|1002|9001|2021-05-02 10:01:01|2021-05-02 10:05:58|60
5|1003|9001|2021-09-05 19:01:01|2021-09-05 19:40:01|49
6|1003|9001|2021-09-05 19:01:01|2021-09-05 19:15:01|70
7|1003|9001|2021-09-06 19:01:01|2021-09-06 19:05:01|80
8|1003|9002|2021-09-09 07:01:02|None|None
答案:
DELETE FROM exam_record
WHERE TIMESTAMPDIFF(MINUTE, start_time, submit_time) < 5
AND score < 60
SQL116 删除记录(二)
描述
现有一张试卷作答记录表exam_record,其中包含多年来的用户作答试卷记录,结构如下表:
作答记录表exam_record:
start_time是试卷开始时间
submit_time 是交卷时间,即结束时间,如果未完成的话,则为空
请删除exam_record表中未完成作答或作答时间小于5分钟整的记录中,开始作答时间最早的3条记录。
后台会通过 SELECT * FROM exam_record 语句来对比结果。
示例1
输入:
drop table if EXISTS exam_record;
CREATE TABLE IF NOT EXISTS exam_record (
id int PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
uid int NOT NULL COMMENT '用户ID',
exam_id int NOT NULL COMMENT '试卷ID',
start_time datetime NOT NULL COMMENT '开始时间',
submit_time datetime COMMENT '提交时间',
score tinyint COMMENT '得分'
)CHARACTER SET utf8 COLLATE utf8_general_ci;
TRUNCATE exam_record;
INSERT INTO exam_record(uid, exam_id, start_time, submit_time, score) VALUES
(1001, 9001, '2020-01-01 22:11:12', '2020-01-01 23:16:12', 50),
(1001, 9002, '2020-01-02 09:01:01', '2020-01-02 09:06:00', 58),
(1001, 9002, '2020-01-02 09:01:01', '2020-01-02 09:05:01', 58),
(1002, 9001, '2021-05-02 10:01:01', '2021-05-02 10:06:58', 60),
(1002, 9002, '2021-06-02 19:01:01', null, null),
(1003, 9001, '2021-09-05 19:01:01', null, null),
(1003, 9001, '2021-09-05 19:01:01', null, null),
(1003, 9002, '2021-09-09 07:01:02', null, null);
复制
输出:
1|1001|9001|2020-01-01 22:11:12|2020-01-01 23:16:12|50
4|1002|9001|2021-05-02 10:01:01|2021-05-02 10:06:58|60
6|1003|9001|2021-09-05 19:01:01|None|None
7|1003|9001|2021-09-05 19:01:01|None|None
8|1003|9002|2021-09-09 07:01:02|None|None
答案:
DELETE FROM exam_record
WHERE submit_time IS NULL
OR TIMESTAMPDIFF(MINUTE, start_time, submit_time) < 5
ORDER BY start_time
LIMIT 3;
# DELETE FROM exam_record
# WHERE submit_time IS NULL
# OR uid IN (
# SELECT DISTINCT uid
# FROM exam_record
# WHERE TIMESTAMPDIFF(MINUTE, start_time, submit_time) < 5
# ORDER BY start_time
# LIMIT 0,3
# )
SQL117 删除记录(三)
描述
现有一张试卷作答记录表exam_record,其中包含多年来的用户作答试卷记录,结构如下表:
请删除exam_record表中所有记录,并重置自增主键。
后台会通过SELECT table_rows, auto_increment FROM information_schema.tables WHERE table_name='exam_record' 语句来对比输出结果
示例1
输入:
drop table if EXISTS exam_record;
CREATE TABLE IF NOT EXISTS exam_record (
id int PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
uid int NOT NULL COMMENT '用户ID',
exam_id int NOT NULL COMMENT '试卷ID',
start_time datetime NOT NULL COMMENT '开始时间',
submit_time datetime COMMENT '提交时间',
score tinyint COMMENT '得分'
)CHARACTER SET utf8 COLLATE utf8_general_ci;
TRUNCATE exam_record;
INSERT INTO exam_record(uid, exam_id, start_time, submit_time, score) VALUES
(1001, 9001, '2020-01-01 22:11:12', '2020-01-01 23:16:12', 50),
(1001, 9002, '2020-01-02 09:01:01', '2020-01-02 09:06:00', 58);
复制
输出:
0|None
答案:
truncate table exam_record;