MySQL表操作
1.介绍
表就相当于文件，表中的一条记录就相当与文件的一行内容，不同的是，表中的一条记录有对应的标题，成为表的字段。
2.创建表
2.1语法
create table 表名(
字段名1 类型[(宽度) 约束条件],
字段名2 类型[(宽度) 约束条件],
字段名3 类型[(宽度) 约束条件],
);
注意：
1. 必须进入数据库中才能创建表
2. 标点符号均为英文标点符号
3. 在同一张表中，字段名是不能相同的
4. 宽度和约束条件为可选项
5. 字段名和类型是必须的
2.2范例
1-使用默认格式创建表
mysql> use python25;
Database changed
mysql> show tables;
Empty set (0.00 sec)
mysql> create table test1(id int,
-> name char(11),
-> sex enum('male', 'female'),
-> hobby set('swiming', 'running', 'basketball'));
Query OK, 0 rows affected (0.02 sec)
mysql> desc test1;
+-------+---------------------------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------------------------------------+------+-----+---------+-------+
| id | int(11) | YES | | NULL | |
| name | char(11) | YES | | NULL | |
| sex | enum('male','female') | YES | | NULL | |
| hobby | set('swiming','running','basketball') | YES | | NULL | |
+-------+---------------------------------------+------+-----+---------+-------+
4 rows in set (0.00 sec)
2-自定义格式创建表
# 指定字符编码
mysql> create table test3 (
-> id int,
-> name char(10),
-> age int,
-> sex enum('male', 'female'),
-> phone char(11),
-> job char(10)
-> ) charset=utf8;
Query OK, 0 rows affected (0.03 sec)
#指定存储引擎
mysql> create table test4 (
-> id int,
-> name char(10),
-> age int,
-> sex enum('male', 'female'),
-> phone char(11),
-> job char(10)
-> ) ENGINE=MyISAM;
Query OK, 0 rows affected (0.01 sec)
3-查看表结构、创建表的语句
# 查看表结构
mysql> show columns from test1;
+-------+---------------------------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------------------------------------+------+-----+---------+-------+
| id | int(11) | YES | | NULL | |
| name | char(11) | YES | | NULL | |
| sex | enum('male','female') | YES | | NULL | |
| hobby | set('swiming','running','basketball') | YES | | NULL | |
+-------+---------------------------------------+------+-----+---------+-------+
4 rows in set (0.00 sec)
mysql> desc test1;
+-------+---------------------------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------------------------------------+------+-----+---------+-------+
| id | int(11) | YES | | NULL | |
| name | char(11) | YES | | NULL | |
| sex | enum('male','female') | YES | | NULL | |
| hobby | set('swiming','running','basketball') | YES | | NULL | |
+-------+---------------------------------------+------+-----+---------+-------+
4 rows in set (0.00 sec)
# 查看创建表的语句
mysql> show create table test1 G;
*************************** 1. row ***************************
Table: test1
Create Table: CREATE TABLE `test1` (
`id` int(11) DEFAULT NULL,
`name` char(11) DEFAULT NULL,
`sex` enum('male','female') DEFAULT NULL,
`hobby` set('swiming','running','basketball') DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)
2.删除表
语法:
DROP TABLE 表名;
注意：删表要谨慎
mysql> show tables; +--------------------+ | Tables_in_python25 | +--------------------+ | test1 | | test2 | | test3 | | test4 | +--------------------+ 4 rows in set (0.00 sec) mysql> drop table test1; Query OK, 0 rows affected (0.01 sec) mysql> drop table test2; Query OK, 0 rows affected (0.01 sec) mysql> show tables; +--------------------+ | Tables_in_python25 | +--------------------+ | test3 | | test4 | +--------------------+ 2 rows in set (0.00 sec)
3.修改表
3.1 修改表名
语法
ALTER TABLE 表名 RENAME 新表名;
范例
mysql> show tables; +--------------------+ | Tables_in_python25 | +--------------------+ | test3 | | test4 | +--------------------+ 2 rows in set (0.00 sec) mysql> alter table test3 rename test1; Query OK, 0 rows affected (0.02 sec) mysql> show tables; +--------------------+ | Tables_in_python25 | +--------------------+ | test1 | | test4 | +--------------------+ 2 rows in set (0.00 sec)
3.2 增加字段
语法
ALTER TABLE 表名 ADD 字段名 数据类型[(宽度) 约束条件], ADD 字段名 数据类型[(宽度) 约束条件];
范例
mysql> desc test1;
+-------+-----------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-----------------------+------+-----+---------+-------+
| id | int(11) | YES | | NULL | |
| name | char(10) | YES | | NULL | |
| age | int(11) | YES | | NULL | |
| sex | enum('male','female') | YES | | NULL | |
| phone | char(11) | YES | | NULL | |
| job | char(10) | YES | | NULL | |
+-------+-----------------------+------+-----+---------+-------+
6 rows in set (0.01 sec)
# 增加hobby、home两个字段
mysql> alter table test1 add hobby set('football', 'running'), add home char(10);
Query OK, 0 rows affected (0.04 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc test1;
+-------+---------------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------------------------+------+-----+---------+-------+
| id | int(11) | YES | | NULL | |
| name | char(10) | YES | | NULL | |
| age | int(11) | YES | | NULL | |
| sex | enum('male','female') | YES | | NULL | |
| phone | char(11) | YES | | NULL | |
| job | char(10) | YES | | NULL | |
| hobby | set('football','running') | YES | | NULL | |
| home | char(10) | YES | | NULL | |
+-------+---------------------------+------+-----+---------+-------+
8 rows in set (0.00 sec)
3.3 删除字段
语法
ALTER TABLE 表名 DROP 字段名;
范例
mysql> desc test1;
+-------+-----------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-----------------------+------+-----+---------+-------+
| id | int(11) | YES | | NULL | |
| name | char(10) | YES | | NULL | |
| age | int(11) | YES | | NULL | |
| sex | enum('male','female') | YES | | NULL | |
| phone | char(11) | YES | | NULL | |
| job | char(10) | YES | | NULL | |
+-------+-----------------------+------+-----+---------+-------+
6 rows in set (0.01 sec)
# 删除hobby、home字段
mysql> alter table test1 add hobby set('football', 'running'), add home char(10);
Query OK, 0 rows affected (0.04 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc test1;
+-------+---------------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------------------------+------+-----+---------+-------+
| id | int(11) | YES | | NULL | |
| name | char(10) | YES | | NULL | |
| age | int(11) | YES | | NULL | |
| sex | enum('male','female') | YES | | NULL | |
| phone | char(11) | YES | | NULL | |
| job | char(10) | YES | | NULL | |
| hobby | set('football','running') | YES | | NULL | |
| home | char(10) | YES | | NULL | |
+-------+---------------------------+------+-----+---------+-------+
8 rows in set (0.00 sec)
3.4 修改字段
语法
ALTER TABLE 表名 MODIFY 字段名 数据类型[(宽度) 约束条件];
ALTER TABLE 表名 CHANGE 旧字段名 新字段名 旧数据类型[(宽度) 约束条件];
ALTER TABLE 表名 CHANGE 旧字段名 新字段名 新数据类型[(宽度) 约束条件];
范例
mysql> desc test1;
+-------+-----------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-----------------------+------+-----+---------+-------+
| id | int(11) | YES | | NULL | |
| name | char(10) | YES | | NULL | |
| age | int(11) | YES | | NULL | |
| sex | enum('male','female') | YES | | NULL | |
| phone | char(11) | YES | | NULL | |
| job | char(10) | YES | | NULL | |
+-------+-----------------------+------+-----+---------+-------+
6 rows in set (0.00 sec)
# 修改job字段的数据类型
mysql> alter table test1 modify job varchar(11);
Query OK, 0 rows affected (0.06 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc test1;
+-------+-----------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-----------------------+------+-----+---------+-------+
| id | int(11) | YES | | NULL | |
| name | char(10) | YES | | NULL | |
| age | int(11) | YES | | NULL | |
| sex | enum('male','female') | YES | | NULL | |
| phone | char(11) | YES | | NULL | |
| job | varchar(11) | YES | | NULL | |
+-------+-----------------------+------+-----+---------+-------+
6 rows in set (0.01 sec)
# 修改job字段为hobby字段
mysql> alter table test1 change job hobby varchar(11);
Query OK, 0 rows affected (0.02 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc test1;
+-------+-----------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-----------------------+------+-----+---------+-------+
| id | int(11) | YES | | NULL | |
| name | char(10) | YES | | NULL | |
| age | int(11) | YES | | NULL | |
| sex | enum('male','female') | YES | | NULL | |
| phone | char(11) | YES | | NULL | |
| hobby | varchar(11) | YES | | NULL | |
+-------+-----------------------+------+-----+---------+-------+
6 rows in set (0.00 sec)
# 修改hobby字段为job字段，且数据类型改为char
mysql> alter table test1 change hobby job char(11);
Query OK, 0 rows affected (0.06 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc test1;
+-------+-----------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-----------------------+------+-----+---------+-------+
| id | int(11) | YES | | NULL | |
| name | char(10) | YES | | NULL | |
| age | int(11) | YES | | NULL | |
| sex | enum('male','female') | YES | | NULL | |
| phone | char(11) | YES | | NULL | |
| job | char(11) | YES | | NULL | |
+-------+-----------------------+------+-----+---------+-------+
6 rows in set (0.01 sec)
3.5 修改字段排列顺序、在增加的时候指定字段位置
语法
ALTER TABLE 表名 ADD 字段名 数据类型 [(宽度) 约束条件] FIRST;
ALTER TABLE 表名 ADD 字段名 数据类型 [(宽度) 约束条件] AFTER 字段名;
ALTER TABLE 表名 CHANGE 字段名 旧字段名 新字段名 新数据类型 [(宽度) 约束条件] FIRST;
ALTER TABLE 表名 MODIFY 字段名 数据类型 [(宽度) 约束条件] AFTER 字段名;
范例
mysql> desc test1;
+-------+-----------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-----------------------+------+-----+---------+-------+
| id | int(11) | YES | | NULL | |
| name | char(10) | YES | | NULL | |
| age | int(11) | YES | | NULL | |
| sex | enum('male','female') | YES | | NULL | |
| phone | char(11) | YES | | NULL | |
| job | char(11) | YES | | NULL | |
+-------+-----------------------+------+-----+---------+-------+
6 rows in set (0.01 sec)
# 在表的开头添加hobby字段
mysql> alter table test1 add hobby char(10) first;
Query OK, 0 rows affected (0.05 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc test1;
+-------+-----------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-----------------------+------+-----+---------+-------+
| hobby | char(10) | YES | | NULL | |
| id | int(11) | YES | | NULL | |
| name | char(10) | YES | | NULL | |
| age | int(11) | YES | | NULL | |
| sex | enum('male','female') | YES | | NULL | |
| phone | char(11) | YES | | NULL | |
| job | char(11) | YES | | NULL | |
+-------+-----------------------+------+-----+---------+-------+
7 rows in set (0.00 sec)
# 在job字段后面添加salary字段
mysql> alter table test1 add salary int after job;
Query OK, 0 rows affected (0.05 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc test1;
+--------+-----------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+--------+-----------------------+------+-----+---------+-------+
| hobby | char(10) | YES | | NULL | |
| id | int(11) | YES | | NULL | |
| name | char(10) | YES | | NULL | |
| age | int(11) | YES | | NULL | |
| sex | enum('male','female') | YES | | NULL | |
| phone | char(11) | YES | | NULL | |
| job | char(11) | YES | | NULL | |
| salary | int(11) | YES | | NULL | |
+--------+-----------------------+------+-----+---------+-------+
8 rows in set (0.00 sec)
# 修改hobby字段名为aihao
mysql> alter table test1 change hobby aihao char(10) first;
Query OK, 0 rows affected (0.02 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc test1;
+--------+-----------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+--------+-----------------------+------+-----+---------+-------+
| aihao | char(10) | YES | | NULL | |
| id | int(11) | YES | | NULL | |
| name | char(10) | YES | | NULL | |
| age | int(11) | YES | | NULL | |
| sex | enum('male','female') | YES | | NULL | |
| phone | char(11) | YES | | NULL | |
| job | char(11) | YES | | NULL | |
| salary | int(11) | YES | | NULL | |
+--------+-----------------------+------+-----+---------+-------+
8 rows in set (0.00 sec)
# 把aihao字段放到salary字段后面
mysql> alter table test1 modify aihao char(10) after salary;
Query OK, 0 rows affected (0.04 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc test1;
+--------+-----------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+--------+-----------------------+------+-----+---------+-------+
| id | int(11) | YES | | NULL | |
| name | char(10) | YES | | NULL | |
| age | int(11) | YES | | NULL | |
| sex | enum('male','female') | YES | | NULL | |
| phone | char(11) | YES | | NULL | |
| job | char(11) | YES | | NULL | |
| salary | int(11) | YES | | NULL | |
| aihao | char(10) | YES | | NULL | |
+--------+-----------------------+------+-----+---------+-------+
8 rows in set (0.00 sec)
4.数据操作
创建表
# 创建语句
create table teacher(
id int primary key,
name char(10) not null,
age int,
hire_date datetime,
sex enum('male', 'female') not null default 'male',
phone char(11) unique,
salary float(8, 2),
hobby set('running', 'football', 'basketball'),
comment varchar(255)
);
# 查看表结构
mysql> desc teacher;
+-----------+----------------------------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------+----------------------------------------+------+-----+---------+-------+
| id | int(11) | NO | PRI | NULL | |
| name | char(10) | NO | | NULL | |
| age | int(11) | YES | | NULL | |
| hire_date | datetime | YES | | NULL | |
| sex | enum('male','female') | NO | | male | |
| phone | char(11) | YES | UNI | NULL | |
| salary | float(8,2) | YES | | NULL | |
| hobby | set('running','football','basketball') | YES | | NULL | |
| comment | varchar(255) | YES | | NULL | |
+-----------+----------------------------------------+------+-----+---------+-------+
9 rows in set (0.00 sec)
4.1 插入数据
语法
插入单行数据，
INSERT INTO 表名 (字段1， 字段2， 字段3...) value (值1, 值2, 值3);
如果不添加字段名称，插入的数据需要与表里的字段一一对应
INSERT INTO 表名 value (值1, 值2, 值3);
插入多行数据
INSERT INTO 表名 values (值1, 值2, 值3),(值1, 值2, 值3),(值1, 值2, 值3);
范例
# 插入单条数据，注意float类型会进行四舍五入
mysql> insert into teacher (id, name, hobby) value (1, 'zhangsan', 'running');
Query OK, 1 row affected (0.42 sec)
mysql> select * from teacher;
+----+----------+------+-----------+------+-------+--------+---------+---------+
| id | name | age | hire_date | sex | phone | salary | hobby | comment |
+----+----------+------+-----------+------+-------+--------+---------+---------+
| 1 | zhangsan | NULL | NULL | male | NULL | NULL | running | NULL |
+----+----------+------+-----------+------+-------+--------+---------+---------+
1 row in set (0.00 sec)
mysql> insert into teacher value (2, 'lisi', 30, '2017-10-20', 'male', '13069948980', 2000, 'basketball', 'haha');
Query OK, 1 row affected (0.15 sec)
mysql> select * from teacher;
+----+----------+------+---------------------+------+-------------+---------+------------+---------+
| id | name | age | hire_date | sex | phone | salary | hobby | comment |
+----+----------+------+---------------------+------+-------------+---------+------------+---------+
| 1 | zhangsan | NULL | NULL | male | NULL | NULL | running | NULL |
| 2 | lisi | 30 | 2017-10-20 00:00:00 | male | 13069948980 | 2000.00 | basketball | haha |
+----+----------+------+---------------------+------+-------------+---------+------------+---------+
2 rows in set (0.03 sec)
# 插入多条数据
mysql> insert into teacher values (3, 'wangwu', 28, '2016-11-20', 'male', '1382333333', 20000, 'football', 'wowo'),
-> (4, 'xiaoli', 28, '2015-11-20', 'female', '13823333333', 20000, 'football', 'wowo');
Query OK, 2 rows affected (0.40 sec)
Records: 2 Duplicates: 0 Warnings: 0
mysql> select * from teacher;
+----+----------+------+---------------------+--------+-------------+----------+------------+---------+
| id | name | age | hire_date | sex | phone | salary | hobby | comment |
+----+----------+------+---------------------+--------+-------------+----------+------------+---------+
| 1 | zhangsan | NULL | NULL | male | NULL | NULL | running | NULL |
| 2 | lisi | 30 | 2017-10-20 00:00:00 | male | 13069948980 | 2000.00 | basketball | haha |
| 3 | wangwu | 28 | 2016-11-20 00:00:00 | male | 1382333333 | 20000.00 | football | wowo |
| 4 | xiaoli | 28 | 2015-11-20 00:00:00 | female | 13823333333 | 20000.00 | football | wowo |
+----+----------+------+---------------------+--------+-------------+----------+------------+---------+
4 rows in set (0.00 sec)
4.2 删除数据
语法
DELETE FROM 表名 WHERE ....;
范例
mysql> select * from teacher; +----+----------+------+---------------------+--------+-------------+----------+------------+---------+ | id | name | age | hire_date | sex | phone | salary | hobby | comment | +----+----------+------+---------------------+--------+-------------+----------+------------+---------+ | 1 | zhangsan | NULL | NULL | male | NULL | NULL | running | NULL | | 2 | lisi | 30 | 2017-10-20 00:00:00 | male | 13069948980 | 2000.00 | basketball | haha | | 3 | wangwu | 28 | 2016-11-20 00:00:00 | male | 1382333333 | 20000.00 | football | wowo | | 4 | xiaoli | 28 | 2015-11-20 00:00:00 | female | 13823333333 | 20000.00 | football | wowo | +----+----------+------+---------------------+--------+-------------+----------+------------+---------+ 4 rows in set (0.00 sec) mysql> delete from teacher where id=1; Query OK, 1 row affected (0.48 sec) mysql> select * from teacher; +----+--------+------+---------------------+--------+-------------+----------+------------+---------+ | id | name | age | hire_date | sex | phone | salary | hobby | comment | +----+--------+------+---------------------+--------+-------------+----------+------------+---------+ | 2 | lisi | 30 | 2017-10-20 00:00:00 | male | 13069948980 | 2000.00 | basketball | haha | | 3 | wangwu | 28 | 2016-11-20 00:00:00 | male | 1382333333 | 20000.00 | football | wowo | | 4 | xiaoli | 28 | 2015-11-20 00:00:00 | female | 13823333333 | 20000.00 | football | wowo | +----+--------+------+---------------------+--------+-------------+----------+------------+---------+ 3 rows in set (0.00 sec)
4.3 更新数据
语法
UPDATE 表名 SET 字段1=值1, 字段2=值2 WHERE ...;
范例
mysql> select * from teacher; +----+--------+------+---------------------+--------+-------------+----------+------------+---------+ | id | name | age | hire_date | sex | phone | salary | hobby | comment | +----+--------+------+---------------------+--------+-------------+----------+------------+---------+ | 2 | lisi | 30 | 2017-10-20 00:00:00 | male | 13069948980 | 2000.00 | basketball | haha | | 3 | wangwu | 28 | 2016-11-20 00:00:00 | male | 1382333333 | 20000.00 | football | wowo | | 4 | xiaoli | 28 | 2015-11-20 00:00:00 | female | 13823333333 | 20000.00 | football | wowo | +----+--------+------+---------------------+--------+-------------+----------+------------+---------+ 3 rows in set (0.00 sec) mysql> update teacher set age=40 where id=2; Query OK, 1 row affected (0.46 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> select * from teacher; +----+--------+------+---------------------+--------+-------------+----------+------------+---------+ | id | name | age | hire_date | sex | phone | salary | hobby | comment | +----+--------+------+---------------------+--------+-------------+----------+------------+---------+ | 2 | lisi | 40 | 2017-10-20 00:00:00 | male | 13069948980 | 2000.00 | basketball | haha | | 3 | wangwu | 28 | 2016-11-20 00:00:00 | male | 1382333333 | 20000.00 | football | wowo | | 4 | xiaoli | 28 | 2015-11-20 00:00:00 | female | 13823333333 | 20000.00 | football | wowo | +----+--------+------+---------------------+--------+-------------+----------+------------+---------+ 3 rows in set (0.00 sec)