MySQL(2):表的增删查改
文章目录
- 增加(insert)
- 全列插入
- 指定列插入
- 查询(select)
- 全列查询
- 指定列查询
- 排列查询
- 分页查询
- 多字段的表达式查询
- 字段的别名查询
- 数据的去重查询
- 条件查询
- 修改数据(update)
- 删除数据(delete)
增加(insert)
全列插入
语法
insert into [表名] values(参数1, 参数2, 参数3 ......);
示例
insert into student values(3, "孙悟空", 22, "1998-2-28 15:08:11", 98, 96.5, 92.03);MariaDB [study]> select * from student;
+------+-----------+------+---------------------+---------+-------+---------+
| id | name | age | birth | chinese | math | english |
+------+-----------+------+---------------------+---------+-------+---------+
| 3 | 孙悟空 | 22 | 1998-02-28 15:08:11 | 98.00 | 96.50 | 92.03 |
+------+-----------+------+---------------------+---------+-------+---------+
1 row in set (0.00 sec)
指定列插入
语法
insert into [表名](列1, 列2, 列3 ......) values(参数1, 参数2, 参数3 ......);
示例
insert into student(id, name, age, chinese, math, english) values(1, "猪八戒", 20, 60, 62.5, 58);MariaDB [study]> select * from student;
+------+-----------+------+---------------------+---------+-------+---------+
| id | name | age | birth | chinese | math | english |
+------+-----------+------+---------------------+---------+-------+---------+
| 3 | 孙悟空 | 22 | 1998-02-28 15:08:11 | 98.00 | 96.50 | 92.03 |
| 1 | 猪八戒 | 20 | NULL | 60.00 | 62.50 | 58.00 |
+------+-----------+------+---------------------+---------+-------+---------+
2 rows in set (0.00 sec)
查询(select)
全列查询
语法
select * from [表名];
示例
select * from student;+------+-----------+------+---------------------+---------+-------+---------+
| id | name | age | birth | chinese | math | english |
+------+-----------+------+---------------------+---------+-------+---------+
| 3 | 孙悟空 | 22 | 1998-02-28 15:08:11 | 98.00 | 96.50 | 92.03 |
| 1 | 猪八戒 | 20 | NULL | 60.00 | 62.50 | 58.00 |
| 1 | 唐僧 | 16 | 2000-10-01 07:21:03 | 80.06 | 82.50 | 86.00 |
| 5 | 沙悟净 | 21 | 1999-05-08 21:10:18 | 72.00 | 75.08 | 70.03 |
| 6 | 白龙马 | 19 | 2000-03-26 14:10:58 | 70.00 | 76.08 | 71.04 |
+------+-----------+------+---------------------+---------+-------+---------+
5 rows in set (0.00 sec)
指定列查询
语法
select 列1, 列2, 列3 ...... from [表名];
示例
select id, name, age from student;+------+-----------+------+
| id | name | age |
+------+-----------+------+
| 3 | 孙悟空 | 22 |
| 1 | 猪八戒 | 20 |
| 1 | 唐僧 | 16 |
| 5 | 沙悟净 | 21 |
| 6 | 白龙马 | 19 |
+------+-----------+------+
5 rows in set (0.00 sec)
排列查询
语法
select * from [表名] order by [依据的列] [asc/desc];
示例
默认升序排列(asc)
select * from student order by id;+------+-----------+------+---------------------+---------+-------+---------+
| id | name | age | birth | chinese | math | english |
+------+-----------+------+---------------------+---------+-------+---------+
| 1 | 猪八戒 | 20 | NULL | 60.00 | 62.50 | 58.00 |
| 1 | 唐僧 | 16 | 2000-10-01 07:21:03 | 80.06 | 82.50 | 86.00 |
| 3 | 孙悟空 | 22 | 1998-02-28 15:08:11 | 98.00 | 96.50 | 92.03 |
| 5 | 沙悟净 | 21 | 1999-05-08 21:10:18 | 72.00 | 75.08 | 70.03 |
| 6 | 白龙马 | 19 | 2000-03-26 14:10:58 | 70.00 | 76.08 | 71.04 |
+------+-----------+------+---------------------+---------+-------+---------+
5 rows in set (0.00 sec)
降序排列(desc)
select * from student order by id desc;+------+-----------+------+---------------------+---------+-------+---------+
| id | name | age | birth | chinese | math | english |
+------+-----------+------+---------------------+---------+-------+---------+
| 6 | 白龙马 | 19 | 2000-03-26 14:10:58 | 70.00 | 76.08 | 71.04 |
| 5 | 沙悟净 | 21 | 1999-05-08 21:10:18 | 72.00 | 75.08 | 70.03 |
| 3 | 孙悟空 | 22 | 1998-02-28 15:08:11 | 98.00 | 96.50 | 92.03 |
| 1 | 猪八戒 | 20 | NULL | 60.00 | 62.50 | 58.00 |
| 1 | 唐僧 | 16 | 2000-10-01 07:21:03 | 80.06 | 82.50 | 86.00 |
+------+-----------+------+---------------------+---------+-------+---------+
5 rows in set (0.00 sec)
分页查询
语法
在所有数据中查询前n条
select * from [表名] limit n;
在所有数据中从第s条开始查询前n条
select * from [表名] limit n offset s;
示例
select * from student limit 3;+------+-----------+------+---------------------+---------+-------+---------+
| id | name | age | birth | chinese | math | english |
+------+-----------+------+---------------------+---------+-------+---------+
| 3 | 孙悟空 | 22 | 1998-02-28 15:08:11 | 98.00 | 96.50 | 92.03 |
| 1 | 猪八戒 | 20 | NULL | 60.00 | 62.50 | 58.00 |
| 1 | 唐僧 | 16 | 2000-10-01 07:21:03 | 80.06 | 82.50 | 86.00 |
+------+-----------+------+---------------------+---------+-------+---------+
3 rows in set (0.00 sec)
select * from student limit 2 offset 2;+------+-----------+------+---------------------+---------+-------+---------+
| id | name | age | birth | chinese | math | english |
+------+-----------+------+---------------------+---------+-------+---------+
| 1 | 唐僧 | 16 | 2000-10-01 07:21:03 | 80.06 | 82.50 | 86.00 |
| 5 | 沙悟净 | 21 | 1999-05-08 21:10:18 | 72.00 | 75.08 | 70.03 |
+------+-----------+------+---------------------+---------+-------+---------+
2 rows in set (0.00 sec)
多字段的表达式查询
语法
select 列1 + 列2 ...... from [表名];
示例
select id, name, chinese + math from student;+------+-----------+----------------+
| id | name | chinese + math |
+------+-----------+----------------+
| 3 | 孙悟空 | 194.50 |
| 1 | 猪八戒 | 122.50 |
| 1 | 唐僧 | 162.56 |
| 5 | 沙悟净 | 147.08 |
| 6 | 白龙马 | 146.08 |
+------+-----------+----------------+
5 rows in set (0.00 sec)
字段的别名查询
语法
select 列1 + 列2 as 别名 from [表名];
示例
select id, name, chinese + math + english as score from student;+------+-----------+--------+
| id | name | score |
+------+-----------+--------+
| 3 | 孙悟空 | 286.53 |
| 1 | 猪八戒 | 180.50 |
| 1 | 唐僧 | 248.56 |
| 5 | 沙悟净 | 217.11 |
| 6 | 白龙马 | 217.12 |
+------+-----------+--------+
5 rows in set (0.00 sec)
数据的去重查询
语法
根据某一字段,进行数据去重后,再查询
select distinct 列 ...... from [表名];
示例
select distinct id from student;+------+
| id |
+------+
| 3 |
| 1 |
| 5 |
| 6 |
+------+
4 rows in set (0.00 sec)
条件查询
比较运算符
操作符 | 描述 |
---|---|
=, <=> | 检测两个值是否相等 |
!=, <> | 检测两个值是否不相等 |
> | 检测左边的值是否大于右边的值 |
< | 检测左边的值是否小于右边的值 |
>= | 检测左边的值是否大于等于右边的值 |
<= | 检测左边的值是否小于等于右边的值 |
like | 模糊匹配 |
in | 判断查询的数据是否符合给与的多个选项数据之一 |
between…and… | 判断查询范围是否介于两个值之间 |
逻辑运算符
操作符 | 描述 |
---|---|
and | 逻辑与,两个条件都满足返回true |
or | 逻辑或,两个条件任意满足一个返回true |
not | 逻辑非,若不满足条件返回true |
语法
select * from [表名] where [条件];
示例
=的使用
select * from student where name = "孙悟空";+------+-----------+------+---------------------+---------+-------+---------+
| id | name | age | birth | chinese | math | english |
+------+-----------+------+---------------------+---------+-------+---------+
| 3 | 孙悟空 | 22 | 1998-02-28 15:08:11 | 98.00 | 96.50 | 92.03 |
+------+-----------+------+---------------------+---------+-------+---------+
1 row in set (0.00 sec)
in的使用
select * from student where name in ("唐僧", "沙悟净");+------+-----------+------+---------------------+---------+-------+---------+
| id | name | age | birth | chinese | math | english |
+------+-----------+------+---------------------+---------+-------+---------+
| 1 | 唐僧 | 16 | 2000-10-01 07:21:03 | 80.06 | 82.50 | 86.00 |
| 5 | 沙悟净 | 21 | 1999-05-08 21:10:18 | 72.00 | 75.08 | 70.03 |
+------+-----------+------+---------------------+---------+-------+---------+
2 rows in set (0.00 sec)
between…and…的使用
select * from student where chinese between 80 and 100;+------+-----------+------+---------------------+---------+-------+---------+
| id | name | age | birth | chinese | math | english |
+------+-----------+------+---------------------+---------+-------+---------+
| 3 | 孙悟空 | 22 | 1998-02-28 15:08:11 | 98.00 | 96.50 | 92.03 |
| 1 | 唐僧 | 16 | 2000-10-01 07:21:03 | 80.06 | 82.50 | 86.00 |
+------+-----------+------+---------------------+---------+-------+---------+
2 rows in set (0.00 sec)
like的使用
select * from student where name like "白%" or math > 80;+------+-----------+------+---------------------+---------+-------+---------+
| id | name | age | birth | chinese | math | english |
+------+-----------+------+---------------------+---------+-------+---------+
| 3 | 孙悟空 | 22 | 1998-02-28 15:08:11 | 98.00 | 96.50 | 92.03 |
| 1 | 唐僧 | 16 | 2000-10-01 07:21:03 | 80.06 | 82.50 | 86.00 |
| 6 | 白龙马 | 19 | 2000-03-26 14:10:58 | 70.00 | 76.08 | 71.04 |
+------+-----------+------+---------------------+---------+-------+---------+
3 rows in set (0.00 sec)
修改数据(update)
注意不能把状态条件忘记,否则修改是针对整张表的
语法
update [表名] set 列1 = val1 ...... where [条件];
示例
update student set birth = "2004-10-1 07:21:03" where name = "唐僧";+------+--------+------+---------------------+---------+-------+---------+
| id | name | age | birth | chinese | math | english |
+------+--------+------+---------------------+---------+-------+---------+
| 1 | 唐僧 | 16 | 2004-10-01 07:21:03 | 80.06 | 82.50 | 86.00 |
+------+--------+------+---------------------+---------+-------+---------+
1 row in set (0.00 sec)
删除数据(delete)
注意不能把状态条件忘记,否则删除是针对整张表的
语法
delete from [表名] where [条件];
示例
delete from student where name = "白龙马";+------+-----------+------+---------------------+---------+-------+---------+
| id | name | age | birth | chinese | math | english |
+------+-----------+------+---------------------+---------+-------+---------+
| 3 | 孙悟空 | 22 | 1998-02-28 15:08:11 | 98.00 | 96.50 | 92.03 |
| 1 | 猪八戒 | 20 | NULL | 60.00 | 62.50 | 58.00 |
| 1 | 唐僧 | 16 | 2004-10-01 07:21:03 | 80.06 | 82.50 | 86.00 |
| 5 | 沙悟净 | 21 | 1999-05-08 21:10:18 | 72.00 | 75.08 | 70.03 |
+------+-----------+------+---------------------+---------+-------+---------+
4 rows in set (0.00 sec)
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