六、MySQL DDL語句介紹：建庫建表，DCL介紹

阿新 • • 發佈：2020-10-23

SQL語句

一、sql語句的語義

DDL：Data Definition Language  #資料定義語言 （create、alter）
DCL：Data Control Language     #資料控制語言 （grant、revoke、commit、rollback）
DML：Data Manipulate Language  #資料操作語言 （insert、delete、update）
DQL：Data Query Language       #資料查詢語言 （select、desc）

二、DDL --資料定義語言

1. create 操作庫

1）檢視語法

mysql> help create database;
Syntax:
CREATE {DATABASE | SCHEMA} [IF NOT EXISTS] db_name [create_specification] ...

create_specification:
   [DEFAULT] CHARACTER SET [=] charset_name | [DEFAULT] COLLATE [=] collation_name

2）建立庫

#1.建庫
mysql> create database db01;
Query OK, 1 row affected (0.00 sec)

#2.建庫2
mysql> create schema db02;
Query OK, 1 row affected (0.00 sec)

#3.建立已存在的庫不報錯
mysql> create database db01;
ERROR 1007 (HY000): Can't create database 'db01'; database exists

mysql> create database IF NOT EXISTS db01;
Query OK, 1 row affected, 1 warning (0.00 sec)

3）檢視建庫語句

mysql> show create database db01;
+----------+-----------------------------------------------------------------+
| Database | Create Database                         |
+----------+-----------------------------------------------------------------+
| db01   | CREATE DATABASE `db01` /*!40100 DEFAULT CHARACTER SET latin1 */ |
+----------+-----------------------------------------------------------------+
1 row in set (0.00 sec)

4）建立庫指定字符集和校驗規則

#1.指定字符集建庫
mysql> create database db03 character set utf8;
Query OK, 1 row affected (0.00 sec)

#2.指定字符集和校驗規則建庫
mysql> create database db04 character set utf8 collate utf8_general_ci;
Query OK, 1 row affected (0.00 sec)

mysql> create database db06 charset utf8 collate utf8_general_ci;
Query OK, 1 row affected (0.00 sec)

# utf8 ：不支援qq表情。
# utf8-mb4 :支援表情
# 校驗碼ci結尾：不區分大小寫
# 校驗碼bin結尾：區分大小寫

5）修改庫

#只需要修改字符集和校驗規則
mysql> alter database db05 character set utf8mb4 collate utf8mb4_general_ci;
Query OK, 1 row affected (0.00 sec)

mysql> show create database db05;
+----------+------------------------------------------------------------------+
| Database | Create Database                          |
+----------+------------------------------------------------------------------+
| db05   | CREATE DATABASE `db05` /*!40100 DEFAULT CHARACTER SET utf8mb4 */ |
+----------+------------------------------------------------------------------+
1 row in set (0.00 sec)

6）刪庫

mysql> drop database db05;
Query OK, 0 rows affected (0.00 sec)

2. create 操作表

1）檢視語法

mysql> help create table;
Syntax:
CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name
   (create_definition,...)
   [table_options]
   [partition_options]

CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name
   [(create_definition,...)]
   [table_options]
   [partition_options]
   [IGNORE | REPLACE]
   [AS] query_expression

CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name
   { LIKE old_tbl_name | (LIKE old_tbl_name) }

2）建表

#1.進入庫
mysql> use test; # 當不在庫裡時。tab鍵無法補全。
Database changed # 當在庫裡時。tab鍵可以補全。

#2.檢視所在庫
mysql> select database();
+------------+
| database() |
+------------+
| test    |
+------------+
1 row in set (0.00 sec)

#3.建表
mysql> create table tb1(id int);
Query OK, 0 rows affected (0.01 sec)

3）資料型別

int         整數          -2^31 --- 2^31-1  (-2147483648 - 2147483647)
tinyint     最小整數      -128 --- 127     #一般用在定義年齡
varchar     字元型別（變長）    #身份證或者名字
char        字元型別（定長）
enum        列舉型別         #性別
datetime    時間型別

4）測試int資料型別

#1.建表
mysql> create table tb1(id int);
Query OK, 0 rows affected (0.01 sec)

#2.指定字符集建表
mysql> create table tb2(id int) charset utf8;
Query OK, 0 rows affected (0.01 sec)

#3.檢視建表語句
mysql> show create table tb2;
+-------+---------------------------------------------------------------------------------------+
| Table | Create Table                                      |
+-------+---------------------------------------------------------------------------------------+
| tb2  | CREATE TABLE `tb2` (
 `id` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+-------+---------------------------------------------------------------------------------------+
1 row in set (0.01 sec)

#4.查看錶結構
mysql> desc tb1;
+-------+---------+------+-----+---------+-------+
| Field | Type   | Null | Key | Default | Extra |
+-------+---------+------+-----+---------+-------+
| id   | int(11) | YES  |   | NULL   |    |
+-------+---------+------+-----+---------+-------+
1 row in set (0.00 sec)

#5.插入資料
mysql> insert tb1 values('11111111111');
ERROR 1264 (22003): Out of range value for column 'id' at row 1

mysql> insert tb1 values('-2147483648');
Query OK, 1 row affected (0.00 sec)

mysql> insert tb1 values('2147483648');
ERROR 1264 (22003): Out of range value for column 'id' at row 1

mysql> insert tb1 values('-2147483649');
ERROR 1264 (22003): Out of range value for column 'id' at row 1

mysql> insert tb1 values('2147483647');
Query OK, 1 row affected (0.00 sec)
#原因：插入的資料超過資料型別的長度

5）測試char和varchar型別

#1.建表
mysql> create table tb1(id int,name varchar(12));
Query OK, 0 rows affected (0.06 sec)

#2.插入資料
mysql> insert into tb1 values('1','邱導');
Query OK, 1 row affected (0.00 sec)

mysql> insert into tb1 values('1','zengzhigaoxiang');
ERROR 1136 (21S01): Column count doesn't match value count at row 1
#字元超過資料型別的限制值

6）測試enum型別

#1.建表
mysql> create table tb4(id int,name varchar(10),sex enum('man','woman'));
Query OK, 0 rows affected (0.03 sec)

#2.插入資料
mysql> insert into tb4 values('1','邱導','man');
Query OK, 1 row affected (0.00 sec)

mysql> insert into tb4 values('2','劉大維','nan');
ERROR 1265 (01000): Data truncated for column 'sex' at row 1
#如果是列舉型別，必須插入型別指定的值，不能插入額外的值

7）建表測試

#建學生表
id
name
sex
age
cometime

#1.建表
mysql> create table student(id int,name varchar(10),sex enum('男','nv'),age tinyint,cometime datetime);
Query OK, 0 rows affected (0.03 sec)

#2.插入資料
mysql> insert into student values('-12573','邱導','男','-18',now());
Query OK, 1 row affected (0.00 sec)

#3.檢視資料
mysql> select * from student;
+--------+--------+------+------+---------------------+
| id   | name  | sex  | age  | cometime       |
+--------+--------+------+------+---------------------+
| -12573 | 邱導  | 男  | -18 | 2020-10-23 18:40:15 |
+--------+--------+------+------+---------------------+
1 row in set (0.00 sec)

8）建表的資料屬性

not null：           非空
primary key：        主鍵（唯一且非空的）
auto_increment：     自增（此列必須是：primary key或者unique key）
unique key：         唯一鍵（單獨的唯一的）
default：            預設值
unsigned：           非負數
comment：            註釋

9）加上資料屬性建表

#1.建表
mysql> create table student(
  -> id int unsigned primary key auto_increment comment '學生id',
  -> name varchar(10) not null comment '學生姓名',
  -> sex enum('男','女') default '男' comment '學生性別',
  -> age tinyint unsigned comment '學生年齡',
  -> cometime datetime default now() comment '入學時間',
  -> class varchar(12) not null comment '學生班級',
  -> status enum('0','1') default 1 comment '學生狀態');
Query OK, 0 rows affected (0.01 sec)

#2.檢視建表語句
mysql> show create table student;
                                     
| student | CREATE TABLE `student` (
 `id` int(10) unsigned NOT NULL AUTO_INCREMENT COMMENT '學生id',
 `name` varchar(10) NOT NULL COMMENT '學生姓名',
 `sex` enum('男','女') DEFAULT '男' COMMENT '學生性別',
 `age` tinyint(3) unsigned DEFAULT NULL COMMENT '學生年齡',
 `cometime` datetime DEFAULT CURRENT_TIMESTAMP COMMENT '入學時間',
 `class` varchar(12) NOT NULL COMMENT '學生班級',
 `status` enum('0','1') DEFAULT '0' COMMENT '學生狀態',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8                |

1 row in set (0.00 sec)

#3.插入資料
mysql> insert into student(name,class) values('邱導','Linux10期');
Query OK, 1 row affected (0.00 sec)
mysql> insert into student(name,class) values('劉大維','Linux10期');
Query OK, 1 row affected (0.00 sec)
mysql> insert into student(name,class) values('虞陳宇','Linux10期');
Query OK, 1 row affected (0.00 sec)
mysql> insert into student(name,age,class) values('周昊','18','Linux10期');
Query OK, 1 row affected (0.00 sec)

#4.檢視資料
mysql> select * from student;
+----+-----------+------+------+---------------------+------------+--------+
| id | name    | sex  | age  | cometime       | class    | status |
+----+-----------+------+------+---------------------+------------+--------+
| 1 | 邱導    | 男  | NULL | 2020-10-23 19:06:25 | Linux10期  | 0    |
| 2 | 邱導    | 男  | NULL | 2020-10-23 19:07:31 | Linux10期  | 0    |
| 3 | 劉大維   | 男  | NULL | 2020-10-23 19:07:57 | Linux10期  | 0    |
| 4 | 虞陳宇   | 男  | NULL | 2020-10-23 19:08:17 | Linux10期  | 0    |
| 5 | 周昊    | 男  |  18 | 2020-10-23 19:09:44 | Linux10期  | 0    |
+----+-----------+------+------+---------------------+------------+--------+
5 rows in set (0.00 sec)

10）刪除表

mysql> drop table student;
Query OK, 0 rows affected (0.00 sec)

11）修改表

#1.修改表字符集
mysql> alter table play charset utf8mb4;
Query OK, 0 rows affected (0.03 sec)
Records: 0  Duplicates: 0  Warnings: 0

#2.修改表名
mysql> alter table play rename student;
Query OK, 0 rows affected (0.01 sec)

#3.給表插入欄位
mysql> alter table student add name varchar(10);

#4.給表插入多個欄位
mysql> alter table student add sex enum('男','女'),add age tinyint;

#5.插入欄位到第一列
mysql> alter table student add id int first;

#6.插入欄位到指定欄位後面
mysql> alter table student add class varchar(12) after id;

#7.刪除欄位
mysql> alter table student drop qiudao;

#8.修改列屬性
mysql> alter table student modify name varchar(20);

#9.修改列的名字和屬性
mysql> alter table student change sex xingbie enum('男','女');

三、DCL--資料控制語言

1.授權命令 grant

#1.授權
grant all on *.* to root@'172.16.1.%' identified by '123';
#應該授權低一點的許可權
grant select,update,insert on database.* to dev@'172.16.1.%' identified by 'Lhd@123456'

#2.檢視使用者許可權
mysql> show grants for root@'localhost';

#3.特殊許可權授權
max_queries_per_hour：一個使用者每小時可發出的查詢數量
max_updates_per_hour：一個使用者每小時可發出的更新數量

max_connections_per_hour：一個使用者每小時可連線到伺服器的次數
mysql> grant all on *.* to lhd@'localhost' identified by '123' with max_connections_per_hour 1;

max_user_connections：允許同時連線數量
mysql> grant all on *.* to test@'localhost' identified by '123' with max_user_connections 2;

2.回收許可權 revoke

#1.回收許可權
mysql> revoke drop on *.* from test@'localhost';

#2.檢視許可權
mysql> show grants for test@'localhost';

#3.所有許可權
SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, GRANT, RELOAD, SHUTDOWN, PROCESS, FILE, REFERENCES, INDEX, ALTER, SHOW DATABASES, SUPER, CREATE TEMPORARY TABLES, LOCK TABLES, EXECUTE, REPLICATION SLAVE, REPLICATION CLIENT, CREATE VIEW, SHOW VIEW, CREATE ROUTINE, ALTER ROUTINE, CREATE USER, EVENT, TRIGGER, CREATE TABLESPACE

3.授權一個超級管理員

mysql> grant all on *.* to superuser@'localhost' identified by 'Lhd@123456' with grant option;

四、DML--資料操作語言

1.insert命令

#1.插入資料之前先看錶結構
mysql> desc student;
+----------+---------------------+------+-----+-------------------+----------------+
| Field   | Type         | Null | Key | Default      | Extra      |
+----------+---------------------+------+-----+-------------------+----------------+
| id    | int(10) unsigned   | NO  | PRI | NULL        | auto_increment |
| name   | varchar(10)     | NO  |   | NULL        |         |
| sex    | enum('男','女')   | YES  |   | 男         |         |
| age    | tinyint(3) unsigned | YES  |   | NULL        |         |
| cometime | datetime       | YES  |   | CURRENT_TIMESTAMP |         |
| class   | varchar(12)     | NO  |   | NULL        |         |
| status  | enum('0','1')    | YES  |   | 0         |         |
+----------+---------------------+------+-----+-------------------+----------------+
7 rows in set (0.00 sec)

#2.insert不規範寫法
mysql> insert student values('4','周昊','男','20','2020-10-23','Linux10','0');
#一個欄位都不能少

#3.規範的寫法（只插入需要的值）
mysql> insert student(name,class) values('邱導','linux10');
mysql> insert student(name,class,age) values('邱導','linux10',20);

#4.規範寫法插入多條資料
mysql> insert student(name,class,age) values('增加','linux10',20),('減少','linux10',30);

2.update語句

#1.修改資料之前一定要確認資料
mysql> select * from student;

#2.修改資料，錯誤寫法
mysql> update student set age='16';

#3.修改資料，正確寫法
mysql> update student set age='18' where id=1;

#4.如果說就是修改表中所有資料
mysql> update student set age='18' where 1=1;

3.delete語句

#1.錯誤語法
mysql> delete from student;

#2.正確寫法
mysql> delete from student where id=1;

#3.刪除
mysql> delete from student where name='增加' and cometime='2020-10-23 20:16:57';

#4.使用狀態列表示已刪除
mysql> update student set status='1' where id=9;
mysql> select * from student where status='0';

4.注意

1.操作資料時一定要檢視資料
2.修改和刪除資料時一定要加條件
3.使用條件時儘量使用主鍵欄位
4.如果沒有主鍵欄位，使用多條件的方式
5.如果有狀態列，使用狀態列表示資料已刪除

六、MySQL DDL語句介紹：建庫建表，DCL介紹

SQL語句一、sql語句的語義 DDL：Data Definition Language#資料定義語言（create、alter）DCL：Data Control Language#資料控制語言（grant、revoke、commit、rollback）DML：Data Manipulate Language#資料操作語