更新记录（一）

Filed	Type	Null	Key	Extra	Default	Comment
id	int(11)	NO	PRI	auto_increment	(NULL)	自增ID
exam_id	int(11)	NO	UNI		(NULL)	试卷ID
tag	char(32)	YES			(NULL)	类别标签
difficulty	char(8)	YES			(NULL)	难度
duration	int(11)	NO			(NULL)	时长
release_time	datetime	YES			(NULL)	发布时间

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');

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

原站题解

Mysql 解法, 执行用时: 36ms, 内存消耗: 6184KB, 提交时间: 2021-12-13

UPDATE examination_info
set tag ='Python' WHERE tag='PYTHON'

Mysql 解法, 执行用时: 36ms, 内存消耗: 6188KB, 提交时间: 2022-01-24

UPDATE examination_info
SET tag='Python'
WHERE tag='PYTHON'

Mysql 解法, 执行用时: 36ms, 内存消耗: 6192KB, 提交时间: 2022-01-25

##第一种
update examination_info
set tag=replace(tag,'PYTHON','Python')
where tag='PYTHON'

Mysql 解法, 执行用时: 36ms, 内存消耗: 6212KB, 提交时间: 2022-01-24

UPDATE examination_info
SET tag='Python' 
WHERE tag='PYTHON'

Mysql 解法, 执行用时: 36ms, 内存消耗: 6224KB, 提交时间: 2022-01-27

update examination_info 
set tag = "Python"
where tag = 'PYTHON';

详情