MySQL表的增删改查基础教程

insert into [表名] (字段1, 字段2,....) value (value1, value2, ...);

insert into [表名] (字段1, 字段2, ....) values
(value1, ...),
(value2, ...),
(value3, ...);

CREATE TABLE exam_result (
 id INT,
 name VARCHAR(20),
 chinese DECIMAL(3,1),
 math DECIMAL(3,1),
 english DECIMAL(3,1)
);

-- 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 into exam_result value ( 1, 'tom', 68, 98, 56); 
insert into exam_result value ( 2, 'jum', 87.5, 78, 77); 

- 插入两条记录，value_list 数量必须和指定列数量及顺序一致
INSERT INTO exam_result (id,name, chinese, math, english) VALUES
 (1,'tom', 67, 98, 56),
 (2,'jum', 87.5, 78, 77),
 (3,'lim', 88, 98.5, 90),
 (4,'tim', 82, 84, 67),
 (5,'huy', 55.5, 85, 45),
 (6,'sun', 70, 73, 78.5),
 (7,'ming', 75, 65, 30);

select * from [表名];

select [指定查询列] from [表名];

select [字段表达式] from [表名];

select colum [as] [列名] from [表名];

--98 分重复了
select math from exam_result;
+------+
| math |
+------+
| 98.0 |
| 78.0 |
| 98.0 |
| 84.0 |
| 85.0 |
| 73.0 |
| 65.0 |
+------+

-- 去重结果
select distinct math from exam_result;
+------+
| math |
+------+
| 98.0 |
| 78.0 |
| 84.0 |
| 85.0 |
| 73.0 |
| 65.0 |
+------+

select * from [表名] order by [排序字段];

select name, math from exam_result order by math desc;
+------+------+
| name | math |
+------+------+
| tom | 98.0 |
| lim | 98.0 |
| huy | 85.0 |
| tim | 84.0 |
| jum | 78.0 |
| sun | 73.0 |
| ming | 65.0 |
+------+------+

select * from exam_result order by math desc, chinese desc;
+------+------+---------+------+---------+
| id | name | chinese | math | english |
+------+------+---------+------+---------+
| 3 | lim | 88.0 | 98.0 | 90.0 |
| 1 | tom | 67.0 | 98.0 | 56.0 |
| 5 | huy | 55.5 | 85.0 | 45.0 |
| 4 | tim | 82.0 | 84.0 | 67.0 |
| 2 | jum | 87.5 | 78.0 | 77.0 |
| 6 | sun | 70.0 | 73.0 | 78.5 |
| 7 | ming | 75.0 | 65.0 | 30.0 |
+------+------+---------+------+---------+

-- 查询英语不及格的同学及英语成绩 ( < 60 )
select name, english from exam_result where english < 60;

-- 查询语文成绩好于英语成绩的同学
select name, chinese, english from exam_result where chinese > english;

-- 查询总分在 200 分以下的同学
select name, chinese + math + english as total from exam_result where chinese + math + english < 200;

-- 查询语文成绩大于80分，且英语成绩大于80分的同学
select * from exam_result where chinese > 80 and english > 80;

-- 查询语文成绩大于80分，或英语成绩大于80分的同学
select * from exam_result where chinese > 80 or english > 80;

-- 查询语文成绩在 [80, 90] 分的同学及语文成绩
select name, chinese from exam_result where chinese BETWEEN 80 AND 90;

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

 -- 查询数学成绩是 58 或者 59 或者 98 或者 99 分的同学及数学成绩
select name, math from exam_result where math in (58, 59, 98, 99);

select name from exam_result where name like 't%';
+------+
| name |
+------+
| tom |
| tim |
+------+

select name from exam_result where name like 't__';
+------+
| name |
+------+
| tom |
| tim |
+------+

select name, chinese from exam_result where chinese like '%8%';
+------+---------+
| name | chinese |
+------+---------+
| jum |  87.5 |
| lim |  88.0 |
| tim |  82.0 |
+------+---------+

 select name from exam_result where id id not null;

-- 最初数据表
select * from exam_result;
+------+------+---------+------+---------+
| id  | name | chinese | math | english |
+------+------+---------+------+---------+
|  1 | tom |  67.0 | 98.0 |  56.0 |
|  2 | jum |  87.5 | 78.0 |  77.0 |
|  3 | lim |  88.0 | 98.0 |  90.0 |
|  4 | tim |  82.0 | 84.0 |  67.0 |
|  5 | huy |  55.5 | 85.0 |  45.0 |
|  6 | sun |  70.0 | 73.0 |  78.5 |
|  7 | ming |  75.0 | 65.0 |  30.0 |
+------+------+---------+------+---------+

-- 前三条记录
select * from exam_result limit 3;
+------+------+---------+------+---------+
| id  | name | chinese | math | english |
+------+------+---------+------+---------+
|  1 | tom |  67.0 | 98.0 |  56.0 |
|  2 | jum |  87.5 | 78.0 |  77.0 |
|  3 | lim |  88.0 | 98.0 |  90.0 |
+------+------+---------+------+---------+

-- 从第三条开始的三条记录
select * from exam_result limit 3 offset 3;
+------+------+---------+------+---------+
| id  | name | chinese | math | english |
+------+------+---------+------+---------+
|  4 | tim |  82.0 | 84.0 |  67.0 |
|  5 | huy |  55.5 | 85.0 |  45.0 |
|  6 | sun |  70.0 | 73.0 |  78.5 |
+------+------+---------+------+---------+

select * from exam_result limit 3 , 4;
+------+------+---------+------+---------+
| id  | name | chinese | math | english |
+------+------+---------+------+---------+
|  4 | tim |  82.0 | 84.0 |  67.0 |
|  5 | huy |  55.5 | 85.0 |  45.0 |
|  6 | sun |  70.0 | 73.0 |  78.5 |
|  7 | ming |  75.0 | 65.0 |  30.0 |
+------+------+---------+------+---------+

update exam_result set math = math + 30 order by chinese + math + english limit 3;

delete from [表名];

-- 删除 ming 同学的考试成绩
delete from exam_result where name = 'ming';

-- 删除整张表
delete from exam_result;

-- 单行插入
insert into [表名] (字段1, ..., 字段N) values (value1, ...,value N);
-- 多行插入
insert into [表名](字段1, ..., 字段N) values
(value1, ...),
(value2, ...),
(value3, ...);

--全表查询
select * from [表名];
--指定列查询
select [列名1, 列名2,...] from [表名];
--查询表达式字段
select [表达式1, 表达式2,...] from [表名];
--别名
select 
--去重 DISTINCT
select distinct [字段] from [表名];
-- 排序ORDER BY
select * from [表名] order by [排序字段];
-- 条件查询WHERE
-- (1)比较运算符 (2)BETWEEN ... AND ... (3)IN (4)IS NULL (5)LIKE (6)AND (7)OR 
(8)NOT
select * from [表名] where [条件];

update [表] set [修改内容1, 修改内容2, ....] where [条件];

delete from [表名] where [条件];