C:\Users\admin>mysql -h localhost -u root -pmysql

mysql: [Warning] Using a password on the command line interface can be insecure.

Welcome to the MySQL monitor. Commands end with ; or \g.

Your MySQL connection id is 4

Server version: 5.7.14 MySQL Community Server (GPL)

Oracle is a registered trademark of Oracle Corporation and/or its

affiliates. Other names may be trademarks of their respective

owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show databases;

+--------------------+

| Database |

+--------------------+

| information_schema |

| mydata |

| mysql |

| performance_schema |

| sys |

| test |

+--------------------+

6 rows in set (0.00 sec)

mysql> use mydata

Database changed

mysql> create table mydata1(

-> id int,

-> name varchar(20),

-> sex boolean

-> );

Query OK, 0 rows affected (0.36 sec)

mysql> desc mydata1;

+-------+-------------+------+-----+---------+-------+

+-------+-------------+------+-----+---------+-------+

| id | int(11) | YES | | NULL | |

| sex | tinyint(1) | YES | | NULL | |

+-------+-------------+------+-----+---------+-------+

3 rows in set (0.02 sec)

mysql> show tables;

+------------------+

| Tables_in_mydata |

+------------------+

| mydata1 |

+------------------+

1 row in set (0.00 sec)

5.1 完整性約束條件

Primary key	主鍵，標識唯一
Foreign key	標識該屬性為該表的外來鍵，聯絡表的主鍵
Not null	屬性不能為空
Unique	屬性的值是唯一的
Auto_increment	值自動增加 ,mysql 的 sql 語句的特色
Default	列設定預設值

5.2 主鍵

單欄位主鍵和多欄位主鍵

mysql> create table mydata2(

-> id int primary key , # 單一欄位主鍵

-> name varchar(20),

-> sex boolean);

Query OK, 0 rows affected (0.23 sec)

mysql> show tables;

+------------------+

| Tables_in_mydata |

+------------------+

| mydata1 |

| mydata2 |

+------------------+

2 rows in set (0.00 sec)

mysql> desc mydata2;

+-------+-------------+------+-----+---------+-------+

+-------+-------------+------+-----+---------+-------+

| id | int(11) | NO | PRI | NULL | |

| sex | tinyint(1) | YES | | NULL | |

+-------+-------------+------+-----+---------+-------+

3 rows in set (0.00 sec)

mysql> alter table mydata2 drop primary key;

Query OK, 0 rows affected (0.68 sec)

Records: 0 Duplicates: 0 Warnings: 0

mysql> desc mydata2;

+-------+-------------+------+-----+---------+-------+

+-------+-------------+------+-----+---------+-------+

| id | int(11) | NO | | NULL | |

| sex | tinyint(1) | YES | | NULL | |

+-------+-------------+------+-----+---------+-------+

3 rows in set (0.00 sec)

mysql> alter table mydata2 add primary key(id,name) ; # 設定多欄位主鍵

Query OK, 0 rows affected (0.49 sec)

Records: 0 Duplicates: 0 Warnings: 0

mysql> desc mydata2;

+-------+-------------+------+-----+---------+-------+

+-------+-------------+------+-----+---------+-------+

| id | int(11) | NO | PRI | NULL | |

| sex | tinyint(1) | YES | | NULL | |

+-------+-------------+------+-----+---------+-------+

3 rows in set (0.00 sec)

也可以在 create table 定義中定義 primary key

mysql> create table mydata3(

-> id int,

-> name varchar(20),

-> sex boolean,

-> primary key(id,name)

-> );

Query OK, 0 rows affected (0.24 sec)

mysql> desc mydata3;

+-------+-------------+------+-----+---------+-------+

+-------+-------------+------+-----+---------+-------+

| id | int(11) | NO | PRI | NULL | |

| sex | tinyint(1) | YES | | NULL | |

+-------+-------------+------+-----+---------+-------+

3 rows in set (0.00 sec)

5.3 外來鍵 foreign key

mysql> create table mydata4(

-> id int primary key,

-> name varchar(30),

-> sex boolean,

-> constraint my_fk foreign key(id) references mydata3(id)

-> );

Query OK, 0 rows affected (0.26 sec)

mysql> desc mydata4;

+-------+-------------+------+-----+---------+-------+

+-------+-------------+------+-----+---------+-------+

| id | int(11) | NO | PRI | NULL | |

| sex | tinyint(1) | YES | | NULL | |

+-------+-------------+------+-----+---------+-------+

3 rows in set (0.00 sec)

5.4 not null 非空

mysql> create table mydata5(

-> id int primary key,

-> name varchar(20) not null);

Query OK, 0 rows affected (0.28 sec)

mysql> desc mydata5;

+-------+-------------+------+-----+---------+-------+

+-------+-------------+------+-----+---------+-------+

| id | int(11) | NO | PRI | NULL | |

+-------+-------------+------+-----+---------+-------+

2 rows in set (0.00 sec)

5.5 unique 唯一性

mysql> create table mydata6(

-> id int primary key,

-> name varchar(20) unique);

Query OK, 0 rows affected (0.35 sec)

mysql> desc mydata6;

+-------+-------------+------+-----+---------+-------+

+-------+-------------+------+-----+---------+-------+

| id | int(11) | NO | PRI | NULL | |

+-------+-------------+------+-----+---------+-------+

2 rows in set (0.00 sec)

5.6 auto_increment

必須為主鍵的一部分

mysql> create table mydata7(

-> id int primary key auto_increment,

-> name varchar(20))

-> ;

Query OK, 0 rows affected (0.24 sec)

mysql> desc mydata7;

+-------+-------------+------+-----+---------+----------------+

+-------+-------------+------+-----+---------+----------------+

| id | int(11) | NO | PRI | NULL | auto_increment |

+-------+-------------+------+-----+---------+----------------+

2 rows in set (0.00 sec)

5.7 預設值

mysql> create table mydata8(

-> id int primary key auto_increment,

-> name varchar(20) unique,

-> address varchar(100) not null,

-> city varchar(20) default 'suzhou',

-> socre float default 0);

Query OK, 0 rows affected (0.35 sec)

mysql> desc mydata8;

+---------+--------------+------+-----+---------+----------------+

+---------+--------------+------+-----+---------+----------------+

| id | int(11) | NO | PRI | NULL | auto_increment |

| socre | float | YES | | 0 | |

+---------+--------------+------+-----+---------+----------------+

5 rows in set (0.04 sec)

5.8 檢視錶結構

mysql> show create table mydata1 \G;

*************************** 1. row ***************************

Table: mydata1

Create Table: CREATE TABLE `mydata1` (

`id` int(11) DEFAULT NULL,

`name` varchar(20) DEFAULT NULL,

`sex` tinyint(1) DEFAULT NULL

) ENGINE=InnoDB DEFAULT CHARSET=latin1

1 row in set (0.00 sec)

ERROR:

No query specified

mysql> desc mydata1;

+-------+-------------+------+-----+---------+-------+

+-------+-------------+------+-----+---------+-------+

| id | int(11) | YES | | NULL | |

| sex | tinyint(1) | YES | | NULL | |

+-------+-------------+------+-----+---------+-------+

3 rows in set (0.00 sec)

5.9 修改表結構

mysql> alter table mydata1 rename to mydata; # 修改表名

Query OK, 0 rows affected (0.23 sec)

mysql> alter table mydata1 modify sex varchar(1); # 修改列屬性

Query OK, 0 rows affected (0.77 sec)

Records: 0 Duplicates: 0 Warnings: 0

mysql> alter table mydata1 change city address varchar(20);

mysql> alter table mydata1 change sex city int; # 修改列名和屬性

Query OK, 0 rows affected (0.94 sec)

Records: 0 Duplicates: 0 Warnings: 0

mysql> alter table mydata1 add city int; # 新增列名

Query OK, 0 rows affected (0.53 sec)

Records: 0 Duplicates: 0 Warnings: 0

mysql> alter table mydata1 add sal int after address; # 在 address 欄位後面加列

Query OK, 0 rows affected (0.35 sec)

Records: 0 Duplicates: 0 Warnings: 0

mysql> alter table mydata1 add uid int first; # 加列為首列

Query OK, 0 rows affected (0.45 sec)

Records: 0 Duplicates: 0 Warnings: 0

mysql> alter table mydata1 drop city; # 刪除列

Query OK, 0 rows affected (0.50 sec)

Records: 0 Duplicates: 0 Warnings: 0

mysql> alter table mydata1 modify sal int after name; # 修改列的位置

Query OK, 0 rows affected (0.53 sec)

Records: 0 Duplicates: 0 Warnings: 0

mysql> alter table mydata1 modify id int first; # 修改為首列

Query OK, 0 rows affected (0.54 sec)

Records: 0 Duplicates: 0 Warnings: 0

CHANGE 對列進行重新命名或更改列的型別，需給定舊的列名稱和新的列名稱、當前的型別 MODIFY 可以改變列的型別，此時不需要重新命名（不需給定新的列名稱）

mysql> alter table mydata1 engine=myisam; # 修改表的儲存引擎

Query OK, 0 rows affected (1.47 sec)

Records: 0 Duplicates: 0 Warnings: 0

mysql> drop table mydata8; # 刪除表

Query OK, 0 rows affected (0.22 sec)

[Mysql] 5.Mysql 建立表

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