MySQL表的增删改查及查询表中数据的三种方式(入门必掌握)

# 创建学生表
CREATE TABLE student(
    id INT,
    name VARCHAR(20),
    age INT,
    sex CHAR(1),
    address VARCHAR(40)
);

#插入两条记录，value_list 数量必须和定义表的列的数量及顺序一致
insert to student values(1,'孙悟空',20,'男','花果山');
insert to student values(2,'猪八戒',18,'男','云栈洞');

#插入两条记录，value_list 数量必须和指定列数量及顺序一致
insert to student (id,name,age,sex,address) values
(3,'沙悟净',18,'男','流沙河'),
(4,'白龙马',16,'男','东海龙宫'),
(5,'哪吒',17,'女','天宫');

update student set sex = '女'

update student set sex = '男' where id = 2;

update student set age = 20,address = '天宫' where id = 2;

delete from student where id = 1;

delete from student;

 创建考试成绩表
DROP TABLE IF EXISTS exam_result;
CREATE TABLE exam_result (
id INT,
name VARCHAR(20),
chinese DECIMAL(3,1),
math DECIMAL(3,1),
english DECIMAL(3,1)
);
-- 插入测试数据
INSERT INTO exam_result (id,name, chinese, math, english) VALUES
(1,'唐三藏', 67, 98, 56),
(2,'孙悟空', 87.5, 78, 77),
(3,'猪悟能', 88, 98.5, 90),
(4,'曹孟德', 82, 84, 67),
(5,'刘玄德', 55.5, 85, 45),
(6,'孙权', 70, 73, 78.5),
(7,'宋公明', 75, 65, 30);

 # *代表所有字段
select * from exam_result;

#字段不用按照指定顺序书写
select id,name from exam_result;

select id,name, chinese + math + english from exam_result;

select id as '学号',name '姓名',chinese '语文',math '数学',english '英语' from exam_result;

select distinct math from exam_result;

select name,math from exam_result order by math desc;

select name,chinese + math + english total from exam_result order total asc; 

select id,name,math from exam_result order by id desc,math desc;

select name,english from exam_result where english < 60;

select name ,chinese,english from exam_result where chinese > english;

select name,chinese + english + math 总分 from exam_result where chinese + english + math <200;

select name,chinese,english from exam_result where chinese > 80 and english > 80;

select name,chinese,english from exam_result where chinese > 80 or english > 80;

select name,chinese,english from exam_result where chinese > 80 or english > 80 and english > 70;
select name,chinese,english from exam_result where (chinese > 80 or english) > 80 and english > 70;

select name,chinese from exam_result where chinese between 80 and 90;

select name,chinese from exam_result where chinese >= 80 and chinese <= 90;

select name from exam_result where name like '%孙%';

select name from exam_result where name like '孙_';

select name from exam_result where english is not null;

select name from exam_rseult where exam_result is null;

select * from exam_result limit 5;
select * from exam_result limit 0,5;

select * from exam_result limit 3,2;

select * from exam_result 0,2;
select * from exam_result 2,2;
select * from exam_result 4,2;