MySQL客戶端工具的使用與MySQL SQL語句

MySQL客戶端工具的使用

1、MySQL程式的組成

  • 客戶端

    • mysql:CLI互動式客戶端程式
    • mycli:CLI互動式客戶端程式;使用sql語句時會有提示資訊
    • mysql_secure_installation:安全初始化,強烈建議安裝完以後執行此命令
    • mysqldump:mysql備份工具
    • mysqladmin:官方提供的shell命令行工具
  • 伺服器端

    • mysqld

2、MySQL監聽地址

伺服器監聽的兩種socket地址:

socket類型 說明
ip socket 默認監聽在tcp的3306埠,支援遠程通訊
unix sock 監聽在sock文件上(/tmp/mysql.sock,/var/lib/mysql/mysql.sock)僅支援本地通訊

3、資料庫配置文件

資料庫配置文件為:/etc/my.cnf和/etc/my.cnf.d目錄下的配置文件

//修改配置文件,配置字元編碼
[root@localhost ~]# vim /etc/my.cnf
    [mysqld]
    character-set-server=utf8mb4
    collation-server=utf8mb4_general_ci

    [client]
    default-character-set=utf8mb4

    [mysql]
    default-character-set=utf8mb4

4、客戶端工具的使用

//語法:mysql [OPTIONS] [database]
//常用的OPTIONS:
    -uUSERNAME      //指定用戶名,默認為root
    -hHOST          //指定伺服器主機,默認為localhost,推薦使用ip地址
    -pPASSWORD      //指定用戶的密碼
    -P              //指定資料庫監聽的埠,如-P3307
    -S              //指定套接字文件位置,多實例部署MySQL時需要使用
    -V              //查看當前使用的mysql版本
    -e              //不登錄mysql執行sql語句後退出,常用於腳本
    --defaults-file=配置文件	//指定MySQL配置文件位置,用於載入客戶端配置
    
[root@localhost ~]# mysql -V
mysql  Ver 14.14 Distrib 5.7.38, for Linux (x86_64) using  EditLine wrapper

[root@localhost ~]# mysql -uroot -pPasswd123! -h127.0.0.1
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: 5.7.38 MySQL Community Server (GPL)

Copyright (c) 2000, 2022, Oracle and/or its affiliates.

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> 
//注意,不推薦直接在命令行里直接用-pPASSWORD的方式登錄,而是使用-p選項,然後互動式輸入密碼

[root@localhost ~]# mysql -uroot -p -h127.0.0.1 -e 'show databases;'
Enter password: 
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
| zsl                |
+--------------------+


MySQL 數據類型

MySQL支援多種類型,大致可以分為三類:數值、日期/時間和字元串(字元)類型。

1、數值類型

MySQL 支援所有標準 SQL 數值數據類型。

這些類型包括嚴格數值數據類型(INTEGER、SMALLINT、DECIMAL 和 NUMERIC),以及近似數值數據類型(FLOAT、REAL 和 DOUBLE PRECISION)。

類型 大小 範圍(有符號) 範圍(無符號) 用途
TINYINT 1 Bytes (-128,127) (0,255) 小整數值
SMALLINT 2 Bytes (-32 768,32 767) (0,65 535) 大整數值
MEDIUMINT 3 Bytes (-8 388 608,8 388 607) (0,16 777 215) 大整數值
INT或INTEGER 4 Bytes (-2 147 483 648,2 147 483 647) (0,4 294 967 295) 大整數值
BIGINT 8 Bytes (-9,223,372,036,854,775,808,9 223 372 036 854 775 807) (0,18 446 744 073 709 551 615) 極大整數值
FLOAT 4 Bytes (-3.402 823 466 E+38,-1.175 494 351 E-38),0,(1.175 494 351 E-38,3.402 823 466 351 E+38) 0,(1.175 494 351 E-38,3.402 823 466 E+38) 單精度 浮點數值
DOUBLE 8 Bytes (-1.797 693 134 862 315 7 E+308,-2.225 073 858 507 201 4 E-308),0,(2.225 073 858 507 201 4 E-308,1.797 693 134 862 315 7 E+308) 0,(2.225 073 858 507 201 4 E-308,1.797 693 134 862 315 7 E+308) 雙精度 浮點數值
DECIMAL 對DECIMAL(M,D) ,如果M>D,為M+2否則為D+2 依賴於M和D的值 依賴於M和D的值 小數值

2、日期和時間類型

表示時間值的日期和時間類型為DATETIME、DATE、TIMESTAMP、TIME和YEAR。

每個時間類型有一個有效值範圍和一個”零”值,當指定不合法的MySQL不能表示的值時使用”零”值。

TIMESTAMP類型有專有的自動更新特性。

類型 大小 ( bytes) 範圍 格式 用途
DATE 3 1000-01-01/9999-12-31 YYYY-MM-DD 日期值
TIME 3 ‘-838:59:59’/’838:59:59’ HH:MM:SS 時間值或持續時間
YEAR 1 1901/2155 YYYY 年份值
DATETIME 8 ‘1000-01-01 00:00:00’ 到 ‘9999-12-31 23:59:59’ YYYY-MM-DD hh:mm:ss 混合日期和時間值
TIMESTAMP 4 ‘1970-01-01 00:00:01’ UTC 到 ‘2038-01-19 03:14:07’ UTC結束時間是第 2147483647 秒,北京時間 2038-1-19 11:14:07,格林尼治時間 2038年1月19日 凌晨 03:14:07 YYYY-MM-DD hh:mm:ss 混合日期和時間值,時間戳

3、字元串類型

字元串類型指CHAR、VARCHAR、BINARY、VARBINARY、BLOB、TEXT、ENUM和SET。

類型 大小 用途
CHAR 0-255 bytes 定長字元串
VARCHAR 0-65535 bytes 變長字元串
TINYBLOB 0-255 bytes 不超過 255 個字元的二進位字元串
TINYTEXT 0-255 bytes 短文本字元串
BLOB 0-65 535 bytes 二進位形式的長文本數據
TEXT 0-65 535 bytes 長文本數據
MEDIUMBLOB 0-16 777 215 bytes 二進位形式的中等長度文本數據
MEDIUMTEXT 0-16 777 215 bytes 中等長度文本數據
LONGBLOB 0-4 294 967 295 bytes 二進位形式的極大文本數據
LONGTEXT 0-4 294 967 295 bytes 極大文本數據

注意

char(n) 和 varchar(n) 中括弧中 n 代表字元的個數,並不代表位元組個數,比如 CHAR(30) 就可以存儲 30 個字元。

CHAR 和 VARCHAR 類型類似,但它們保存和檢索的方式不同。它們的最大長度和是否尾部空格被保留等方面也不同。在存儲或檢索過程中不進行大小寫轉換。

BINARY 和 VARBINARY 類似於 CHAR 和 VARCHAR,不同的是它們包含二進位字元串而不要非二進位字元串。也就是說,它們包含位元組字元串而不是字元字元串。這說明它們沒有字符集,並且排序和比較基於列值位元組的數值值。

BLOB 是一個二進位大對象,可以容納可變數量的數據。有 4 種 BLOB 類型:TINYBLOB、BLOB、MEDIUMBLOB 和 LONGBLOB。它們區別在於可容納存儲範圍不同。

有 4 種 TEXT 類型:TINYTEXT、TEXT、MEDIUMTEXT 和 LONGTEXT。對應的這 4 種 BLOB 類型,可存儲的最大長度不同,可根據實際情況選擇。

MySQL SQL語句

1、DDL操作

1.1 資料庫DDL操作
//創建資料庫
//語法:create database [if not exists] 'da_name';

//創建資料庫zsl
mysql> create database zsl;
Query OK, 1 row affected (0.00 sec)

//查看當前實例有哪些資料庫
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
| zsl                |
+--------------------+
5 rows in set (0.00 sec)

//刪除資料庫
//語法:drop database [if exists] 'da_name';

//刪除資料庫zsl
mysql> drop database zsl;
Query OK, 0 rows affected (0.00 sec)

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
4 rows in set (0.00 sec)

//創建資料庫時,設置資料庫的字符集:
//character set:指定資料庫採用的字符集,utf8不能寫成utf-8,建議使用utf8mb4字符集
//collate:指定資料庫字符集的排序規則,utf8mb4的默認排序規則為utf8mb4_general_ci(通過show character set查看)
mysql> create database dbtest character set utf8mb4 collate utf8mb4_general_ci;

//資料庫客戶端字元編碼需要和服務端字符集保持一致
//SET NAMES:指定客戶端字符集
mysql> SET NAMES utf8mb4;

//字符集配置都可寫入MySQL配置文件中啟動MySQL服務時自動載入
1.2 表DDL操作
//創建表
//語法:create table table_name (col1 datatype 修飾符,col2 datatype 修飾符) ENGINE='存儲引擎類型';

//在資料庫lsz里創建表lsztable
mysql> CREATE DATABASE IF NOT EXISTS lsz;		//創建資料庫lsz
Query OK, 1 row affected (0.00 sec)

mysql> use lsz;		//進入lsz資料庫
Database changed

//創建lsztable表
mysql> create table lsztable (id int(10) not null,name varchar(100) not null,age tinyint);
Query OK, 0 rows affected (0.00 sec)

//查看當前資料庫有哪些表
mysql> show tables;
+---------------+
| Tables_in_lsz |
+---------------+
| lsztable      |
+---------------+
1 row in set (0.00 sec)

//刪除表
//語法:drop table [ if exists ] 'table_name';

//刪除表lsztable
mysql> drop table lsztable;
Query OK, 0 rows affected (0.01 sec)

mysql> show tables;
Empty set (0.00 sec)

//創建表時,設置欄位、表的字元編碼
mysql> create table tb_course(id int not null primary key auto_increment,course_name vaarchar(50)) default character set utf8 collate utf8_general-ci;

1.3 用戶操作

MySQL用戶帳號由兩部分組成,如’USERNAME’@’HOST’,表示此USERNAME只能從此HOST上遠程登錄;HOST用於限制此用戶可通過哪些主機遠程連接mysql程式。

HOST的值可為:

  • IP地址,如:172.16.12.129
  • 通配符
    • %:匹配任意長度的任意字元,常用於設置允許從任何主機登錄
    • _:匹配任意單個字元
//資料庫用戶創建
//語法:create user 'username'@'host' [identified by 'password'];

//創建資料庫用戶zsl
mysql> create user 'zsl'@'127.0.0.1' identified by 'Passwd123!';
Query OK, 0 rows affected (0.00 sec)

//使用新創建的用戶和密碼登錄
[root@localhost ~]# mysql -uzsl -pPasswd123! -h127.0.0.1
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 5
Server version: 5.7.38 MySQL Community Server (GPL)

Copyright (c) 2000, 2022, Oracle and/or its affiliates.

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> 

//刪除資料庫用戶
//語法:drop user 'username'@'host'; 

//刪除資料庫用戶zsl
mysql> drop user 'zsl'@'127.0.0.1';
Query OK, 0 rows affected (0.00 sec)
1.4 查看命令show
mysql> show character set;		//查看支援的所有字符集
+----------+---------------------------------+---------------------+--------+
| Charset  | Description                     | Default collation   | Maxlen |
+----------+---------------------------------+---------------------+--------+
| big5     | Big5 Traditional Chinese        | big5_chinese_ci     |      2 |
| dec8     | DEC West European               | dec8_swedish_ci     |      1 |
| cp850    | DOS West European               | cp850_general_ci    |      1 |
| hp8      | HP West European                | hp8_english_ci      |      1 |
| koi8r    | KOI8-R Relcom Russian           | koi8r_general_ci    |      1 |
| latin1   | cp1252 West European            | latin1_swedish_ci   |      1 |
......
......

mysql> show variables like '%char%';		//查看客戶端的字元編碼
+--------------------------------------+----------------------------+
| Variable_name                        | Value                      |
+--------------------------------------+----------------------------+
| character_set_client                 | utf8                       |
| character_set_connection             | utf8                       |
| character_set_database               | latin1                     |
| character_set_filesystem             | binary                     |
| character_set_results                | utf8                       |
| character_set_server                 | latin1                     |
| character_set_system                 | utf8                       |
| character_sets_dir                   | /usr/share/mysql/charsets/ |
| validate_password_special_char_count | 1                          |
+--------------------------------------+----------------------------+
9 rows in set (0.00 sec)

mysql> select charset(id) from lsztable;		//查看某表中某欄位使用的字元編碼
......
......

mysql> show engines;		//查看當前資料庫支援的所有存儲引擎
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| Engine             | Support | Comment                                                        | Transactions | XA   | Savepoints |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| InnoDB             | DEFAULT | Supports transactions, row-level locking, and foreign keys     | YES          | YES  | YES        |
| MRG_MYISAM         | YES     | Collection of identical MyISAM tables                          | NO           | NO   | NO         |
| MEMORY             | YES     | Hash based, stored in memory, useful for temporary tables      | NO           | NO   | NO         |
| BLACKHOLE          | YES     | /dev/null storage engine (anything you write to it disappears) | NO           | NO   | NO         |
| MyISAM             | YES     | MyISAM storage engine                                          | NO           | NO   | NO         |
| CSV                | YES     | CSV storage engine                                             | NO           | NO   | NO         |
| ARCHIVE            | YES     | Archive storage engine                                         | NO           | NO   | NO         |
| PERFORMANCE_SCHEMA | YES     | Performance Schema                                             | NO           | NO   | NO         |
| FEDERATED          | NO      | Federated MySQL storage engine                                 | NULL         | NULL | NULL       |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
9 rows in set (0.00 sec)

mysql> show databases;		//查看資料庫資訊
+--------------------+
| Database           |
+--------------------+
| information_schema |
| lsz                |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
5 rows in set (0.00 sec)

mysql> show tables from lsz;		//不進入某資料庫而列出其包含的所有表
+---------------+
| Tables_in_lsz |
+---------------+
| lsztable      |
+---------------+
1 row in set (0.00 sec)

//查看錶結構
//語法:desc [db_name.]table_name;

mysql> desc lsz.lsztable;
+-------+--------------+------+-----+---------+-------+
| Field | Type         | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| id    | int(10)      | NO   |     | NULL    |       |
| name  | varchar(100) | NO   |     | NULL    |       |
| age   | tinyint(4)   | YES  |     | NULL    |       |
+-------+--------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

//查看某表的創建命令,可以看到創建表時設置的參數
//語法:show create table table_name;

mysql> show create table lsz.lsztable;
+----------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table    | Create Table                                                                                                                                              |
+----------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
| lsztable | CREATE TABLE `lsztable` (
  `id` int(10) NOT NULL,
  `name` varchar(100) NOT NULL,
  `age` tinyint(4) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+----------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

//查看某表的狀態
//語法:show table status like 'table_name'\G

mysql> show table status like 'lsztable'\G;
*************************** 1. row ***************************
           Name: lsztable
         Engine: InnoDB
        Version: 10
     Row_format: Dynamic
           Rows: 0
 Avg_row_length: 0
    Data_length: 16384
Max_data_length: 0
   Index_length: 0
      Data_free: 0
 Auto_increment: NULL
    Create_time: 2022-07-26 08:40:01
    Update_time: NULL
     Check_time: NULL
      Collation: latin1_swedish_ci
       Checksum: NULL
 Create_options: 
        Comment: 
1 row in set (0.00 sec)

ERROR: 
No query specified
1.5 alter修改操作
//修改資料庫屬性
//語法:alter adtabase 'db_name' character set charset_name | collate collation_name

//修改資料庫字符集為utf8
mysql> alter database lsz character set utf8;
Query OK, 1 row affected (0.01 sec)

//修改表
//語法:alter table <table_name> [option]

//給lsztable表添加新的一列,先查看錶結構
mysql> desc lsztable;
+-------+--------------+------+-----+---------+-------+
| Field | Type         | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| id    | int(10)      | NO   |     | NULL    |       |
| name  | varchar(100) | NO   |     | NULL    |       |
| age   | tinyint(4)   | YES  |     | NULL    |       |
+-------+--------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

//給lsztable表添加一列'phone'
mysql> alter table lsztable add phone int(11);
Query OK, 0 rows affected (0.02 sec)
Records: 0  Duplicates: 0  Warnings: 0

//查看錶結構
mysql> desc lsztable;
+-------+--------------+------+-----+---------+-------+
| Field | Type         | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| id    | int(10)      | NO   |     | NULL    |       |
| name  | varchar(100) | NO   |     | NULL    |       |
| age   | tinyint(4)   | YES  |     | NULL    |       |
| phone | int(11)      | YES  |     | NULL    |       |
+-------+--------------+------+-----+---------+-------+
4 rows in set (0.00 sec)

//修改lsztable表中'phone'列為'sex'
mysql> alter table lsztable change phone sex varchar(4);
Query OK, 0 rows affected (0.01 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> desc lsztable;
+-------+--------------+------+-----+---------+-------+
| Field | Type         | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| id    | int(10)      | NO   |     | NULL    |       |
| name  | varchar(100) | NO   |     | NULL    |       |
| age   | tinyint(4)   | YES  |     | NULL    |       |
| sex   | varchar(4)   | YES  |     | NULL    |       |
+-------+--------------+------+-----+---------+-------+
4 rows in set (0.00 sec)

//修改表名為zsltable
mysql> alter table lsztable rename to zsltable;
Query OK, 0 rows affected (0.00 sec)

mysql> show tables;
+---------------+
| Tables_in_lsz |
+---------------+
| zsltable      |
+---------------+
1 row in set (0.00 sec)

//修改資料庫字元編碼
mysql> altar database dbtest character set utf8 collate utf8_general_ci;

//修改表字元編碼
mysql> altar table tbtest character set utf8 collate utf8_general_ci;
1.6 獲取幫助
//獲取命令使用幫助
//語法:help commond;

mysql> help create table;       //獲取創建表的幫助
Name: 'CREATE TABLE'
Description:
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
 ......
 ......

2、DML操作

DML操作包括增(INSERT)、刪(DELETE)、改(UPDATE)、查(SELECT),均屬針對錶的操作。

2.1 insert語句
//DML操作之增操作insert
//語法:inster [into] table_name [(column_name,...)] {values | value} (value1,...),(...),...

mysql> use lsz;
Database changed

//一次插入一條記錄
mysql> insert zsltable (id,name,age,sex) value(1,'tom',20,'nan');
Query OK, 1 row affected (0.00 sec)

//一次插入多條記錄
mysql> insert zsltable (id,name,age,sex) values(2,'jerry',23,'nv'),(3,'zsl',18,'nan'),(4,'sean',null,'nv');
Query OK, 3 rows affected (0.00 sec)
Records: 3  Duplicates: 0  Warnings: 0
2.2 select語句

欄位column匹配方式:

表示符 含義
* 所有欄位
as 欄位別名,如col1 AS alias1 當表名很長時用別名代替

條件判斷語句WHERE:

操作類型 常用操作符
操作符 >,<,>=,<=,=,!=
BETWEEN column# AND column#
LIKE:模糊匹配 RLIKE:基於正則表達式進行模式匹配
IS NOT NULL:非空
IS NULL:空
條件邏輯操作 AND
OR
NOT

ORDER BY:排序,默認為升序(ASC)

ORDER BY語句 意義
ORDER BY 『column_name’ 根據column_name進行升序排序
ORDER BY ‘column_name’ DESC 根據column_name進行降序排序
ORDER BY 』column_name’ LIMIT 2 根據column_name進行升序排序 並只取前2個結果
ORDER BY 『column_name’ LIMIT 1,2 根據column_name進行升序排序 並且略過第1個結果取後面的2個結果
/DML操作之查操作select
//語法:SELECT column1,column2,... FROM table_name [WHERE clause] [ORDER BY 'column_name' [DESC]] [LIMIT [m,]n];

#進入資料庫
mysql> use lsz;
Database changed

#查看錶所有的內容
mysql> select * from zsltable;
+----+-------+------+------+
| id | name  | age  | sex  |
+----+-------+------+------+
|  1 | tom   |   20 | nan  |
|  2 | jerry |   23 | nv   |
|  3 | zsl   |   18 | nan  |
|  4 | sean  | NULL | nv   |
+----+-------+------+------+
4 rows in set (0.00 sec)

#查看錶的name欄位內容
mysql> select name from zsltable;
+-------+
| name  |
+-------+
| tom   |
| jerry |
| zsl   |
| sean  |
+-------+
4 rows in set (0.00 sec)

#根據age欄位內容從低到高排列
mysql> select * from zsltable order by age;
+----+-------+------+------+
| id | name  | age  | sex  |
+----+-------+------+------+
|  4 | sean  | NULL | nv   |
|  3 | zsl   |   18 | nan  |
|  1 | tom   |   20 | nan  |
|  2 | jerry |   23 | nv   |
+----+-------+------+------+
4 rows in set (0.00 sec)

#根據age欄位內容從高到低排列
mysql> select * from zsltable order by age desc;
+----+-------+------+------+
| id | name  | age  | sex  |
+----+-------+------+------+
|  2 | jerry |   23 | nv   |
|  1 | tom   |   20 | nan  |
|  3 | zsl   |   18 | nan  |
|  4 | sean  | NULL | nv   |
+----+-------+------+------+
4 rows in set (0.00 sec)

#根據age欄位內容從低到高排列取前兩行
mysql> select * from zsltable order by age limit 2;
+----+------+------+------+
| id | name | age  | sex  |
+----+------+------+------+
|  4 | sean | NULL | nv   |
|  3 | zsl  |   18 | nan  |
+----+------+------+------+
2 rows in set (0.00 sec)

#根據age欄位內容從低到高排列,跳過第一行取下一行
mysql> select * from zsltable order by age limit 1,1;
+----+------+------+------+
| id | name | age  | sex  |
+----+------+------+------+
|  3 | zsl  |   18 | nan  |
+----+------+------+------+
1 row in set (0.00 sec)

#查看錶中年齡大於等於20的行;
mysql> select * from zsltable where age >=20;
+----+-------+------+------+
| id | name  | age  | sex  |
+----+-------+------+------+
|  1 | tom   |   20 | nan  |
|  2 | jerry |   23 | nv   |
+----+-------+------+------+
2 rows in set (0.00 sec)

#查看錶中年齡大於等於20且名字叫jerry的行;
mysql> select * from zsltable where age >=20 and name = 'jerry';
+----+-------+------+------+
| id | name  | age  | sex  |
+----+-------+------+------+
|  2 | jerry |   23 | nv   |
+----+-------+------+------+
1 row in set (0.00 sec)

#查看錶中年齡18到23的行
mysql> select * from zsltable where age between 18 and 23;
+----+-------+------+------+
| id | name  | age  | sex  |
+----+-------+------+------+
|  1 | tom   |   20 | nan  |
|  2 | jerry |   23 | nv   |
|  3 | zsl   |   18 | nan  |
+----+-------+------+------+
3 rows in set (0.00 sec)

#查看錶中年齡不為空的
mysql> select * from zsltable where age is not null;
+----+-------+------+------+
| id | name  | age  | sex  |
+----+-------+------+------+
|  1 | tom   |   20 | nan  |
|  2 | jerry |   23 | nv   |
|  3 | zsl   |   18 | nan  |
+----+-------+------+------+
3 rows in set (0.00 sec)

#查看錶中年齡為空的
mysql> select * from zsltable where age is null;
+----+------+------+------+
| id | name | age  | sex  |
+----+------+------+------+
|  4 | sean | NULL | nv   |
+----+------+------+------+
1 row in set (0.00 sec)

#查找name欄位含有z的行
mysql> select * from zsltable where name like '%z%';
+----+------+------+------+
| id | name | age  | sex  |
+----+------+------+------+
|  3 | zsl  |   18 | nan  |
+----+------+------+------+
1 row in set (0.00 sec)
2.3 update語句
//DML操作之改操作update
//語法:UPDATE table_name SET column1 = new_value1[,column2 = new_value2,...] [WHERE clause] [ORDER BY 'column_name' [DESC]] [LIMIT [m,]n];

mysql> select * from zsltable;
+----+-------+------+------+
| id | name  | age  | sex  |
+----+-------+------+------+
|  1 | tom   |   20 | nan  |
|  2 | jerry |   23 | nv   |
|  3 | zsl   |   18 | nan  |
|  4 | sean  | NULL | nv   |
+----+-------+------+------+
4 rows in set (0.00 sec)

mysql> update zsltable set age=25 where name = 'sean';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> select * from zsltable where name = 'sean';
+----+------+------+------+
| id | name | age  | sex  |
+----+------+------+------+
|  4 | sean |   25 | nv   |
+----+------+------+------+
1 row in set (0.00 sec)
2.4 delete語句
//DML操作之刪操作delete
//語法:DELETE FROM table_name [WHERE clause] [ORDER BY 'column_name' [DESC]] [LIMIT [m,]n];

mysql> select * from zsltable;
+----+-------+------+------+
| id | name  | age  | sex  |
+----+-------+------+------+
|  1 | tom   |   20 | nan  |
|  2 | jerry |   23 | nv   |
|  3 | zsl   |   18 | nan  |
|  4 | sean  |   25 | nv   |
+----+-------+------+------+
4 rows in set (0.00 sec)

mysql> delete from zsltable where id =3;		//刪除某條記錄
Query OK, 1 row affected (0.00 sec)

mysql> select * from zsltable;
+----+-------+------+------+
| id | name  | age  | sex  |
+----+-------+------+------+
|  1 | tom   |   20 | nan  |
|  2 | jerry |   23 | nv   |
|  4 | sean  |   25 | nv   |
+----+-------+------+------+
3 rows in set (0.00 sec)

mysql> delete from zsltable;		 //刪除整張表的內容
Query OK, 3 rows affected (0.01 sec)

mysql> select * from zsltable;
Empty set (0.00 sec)

mysql> desc zsltable;
+-------+--------------+------+-----+---------+-------+
| Field | Type         | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| id    | int(10)      | NO   |     | NULL    |       |
| name  | varchar(100) | NO   |     | NULL    |       |
| age   | tinyint(4)   | YES  |     | NULL    |       |
| sex   | varchar(4)   | YES  |     | NULL    |       |
+-------+--------------+------+-----+---------+-------+
4 rows in set (0.00 sec)
2.5 truncate語句

truncate與delete的區別:

語句類型 特點
delete DELETE刪除表內容時僅刪除內容,但會保留表結構 DELETE語句每次刪除一行,並在事務日誌中為所刪除的每行記錄一項 可以通過回滾事務日誌恢複數據 非常佔用空間
truncate 刪除表中所有數據,且無法恢復 表結構、約束和索引等保持不變,新添加的行計數值重置為初始值 執行速度比DELETE快,且使用的系統和事務日誌資源少 通過釋放存儲表數據所用的數據頁來刪除數據,並且只在事務日誌中記錄頁的釋放 對於有外鍵約束引用的表,不能使用TRUNCATE TABLE刪除數據 不能用於加入了索引視圖的表
//語法:TRUNCATE table_name;

mysql> select * from zsltable;
+----+-------+------+------+
| id | name  | age  | sex  |
+----+-------+------+------+
|  1 | tom   |   20 | nan  |
|  2 | jerry |   23 | nv   |
|  3 | zsl   |   18 | nan  |
|  4 | sean  |   25 | nv   |
+----+-------+------+------+
4 rows in set (0.00 sec)

mysql> truncate zsltable;
Query OK, 0 rows affected (0.01 sec)

mysql> select * from zsltable;
Empty set (0.00 sec)

mysql> select * from zsltable;
Empty set (0.00 sec)

mysql> desc zsltable;
+-------+--------------+------+-----+---------+-------+
| Field | Type         | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| id    | int(10)      | NO   |     | NULL    |       |
| name  | varchar(100) | NO   |     | NULL    |       |
| age   | tinyint(4)   | YES  |     | NULL    |       |
| sex   | varchar(4)   | YES  |     | NULL    |       |
+-------+--------------+------+-----+---------+-------+
4 rows in set (0.00 sec)

3、DCL操作

3.1 創建授權grant

許可權類型(priv_type)

許可權類型 含義
ALL 所有許可權
SELECT 讀取內容的許可權
INSERT 插入內容的許可權
UPDATE 更新內容的許可權
DELETE 刪除內容的許可權

指定要操作的對象db_name.table_name

表示方式 含義
. 所有庫的所有表
db_name 指定庫的所有表
db_name.table_name 指定庫的指定表

WITH GRANT OPTION:被授權的用戶可將自己的許可權副本轉贈給其他用戶,說白點就是將自己的許可權完全複製給另一個用戶。不建議使用。

//語法:GRANT priv_type,... ON [object_type] db_name.table_name TO 『username'@'host' [IDENTIFIED BY 'password'] [WITH GRANT OPTION];

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| lsz                |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
5 rows in set (0.00 sec)

//授權lsz用戶在資料庫本機上登錄訪問所有資料庫
mysql> GRANT ALL ON *.* TO 'lsz'@'localhost' IDENTIFIED BY 'Passwd123!';
Query OK, 0 rows affected, 1 warning (0.00 sec)

//也可表示為:
mysql> GRANT ALL ON *.* TO 'lsz'@'127.0.0.1' IDENTIFIED BY 'Passwd123!';
Query OK, 0 rows affected, 1 warning (0.00 sec)

//授權lsz用戶在192.168.111.135上遠程登錄訪問hzz資料庫
mysql> GRANT ALL ON lsz.* TO 'lsz'@'192.168.111.135' IDENTIFIED BY 'Passwd123!';
Query OK, 0 rows affected, 1 warning (0.00 sec)

//授權lsz用戶在所有位置上遠程登錄訪問lsz資料庫
mysql> GRANT ALL ON lsz.* TO 'lsz'@'%' IDENTIFIED BY 'Passwd123!';
Query OK, 0 rows affected, 1 warning (0.00 sec)

//刷新授權表
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
3.2 查看授權
//查看當前登錄用戶的授權資訊
mysql> show grants;
+---------------------------------------------------------------------+
| Grants for root@localhost                                           |
+---------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' WITH GRANT OPTION |
| GRANT PROXY ON ''@'' TO 'root'@'localhost' WITH GRANT OPTION        |
+---------------------------------------------------------------------+
2 rows in set (0.00 sec)

//查看指定用戶lsz的授權資訊
mysql> show grants for 'lsz'@'localhost';
+--------------------------------------------------+
| Grants for lsz@localhost                         |
+--------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'lsz'@'localhost' |
+--------------------------------------------------+
1 row in set (0.00 sec)
3.3 取消授權REVOKE
//語法:REVOKE priv_type,... ON db_name.table_name FROM 'username'@'host';

mysql> revoke all on *.* from 'lsz'@'192.168.111.135';
Query OK, 0 rows affected (0.00 sec)

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

注意:mysql服務進程啟動時會讀取mysql庫中的所有授權表至記憶體中:

  • GRANT或REVOKE等執行許可權操作會保存於表中,mysql的服務進程會自動重讀授權表,並更新至記憶體中
  • 對於不能夠或不能及時重讀授權表的命令,可手動讓mysql的服務進程重讀授權表
mysql> FLUSH PRIVILEGES;

實戰案例

1.搭建mysql服務

[root@localhost ~]# wget //dev.mysql.com/get/mysql57-community-release-el7-11.noarch.rpm
[root@localhost ~]# rpm -Uvh mysql57-community-release-el7-11.noarch.rpm 
[root@localhost ~]# dnf -y install mysql-community-server mysql-community-client mysql-community-common mysql-community-devel  --nogpgcheck
[root@localhost ~]# systemctl enable --now mysqld

2.創建一個以你名字為名的資料庫,並創建一張表student,該表包含三個欄位(id,name,age),表結構如下:

mysql> desc student;
+-------+--------------+------+-----+---------+----------------+
| Field | Type         | Null | Key | Default | Extra          |
+-------+--------------+------+-----+---------+----------------+
| id    | int(11)      | NO   | PRI | NULL    | auto_increment |
| name  | varchar(100) | NO   |     | NULL    |                |
| age   | tinyint(4)   | YES  |     | NULL    |                |
+-------+--------------+------+-----+---------+----------------+
3 rows in set (0.01 sec)
mysql> create database zsl;
Query OK, 1 row affected (0.00 sec)

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| lsz                |
| mysql              |
| performance_schema |
| sys                |
| zsl                |
+--------------------+
6 rows in set (0.00 sec)

mysql> create table student(id int(11) primary key auto_increment,name varchar(100) not null,age tinyint(4));
Query OK, 0 rows affected (0.01 sec)

mysql> desc student;
+-------+--------------+------+-----+---------+----------------+
| Field | Type         | Null | Key | Default | Extra          |
+-------+--------------+------+-----+---------+----------------+
| id    | int(11)      | NO   | PRI | NULL    | auto_increment |
| name  | varchar(100) | NO   |     | NULL    |                |
| age   | tinyint(4)   | YES  |     | NULL    |                |
+-------+--------------+------+-----+---------+----------------+
3 rows in set (0.00 sec)

3.查看下該新建的表有無內容(用select語句)

mysql> select * from student;
Empty set (0.00 sec)

4.往新建的student表中插入數據(用insert語句),結果應如下所示:

+----+-------------+------+
| id | name        | age  |
+----+-------------+------+
|  1 | tom         |   20 |
|  2 | jerry       |   23 |
|  3 | wangqing    |   25 |
|  4 | sean        |   28 |
|  5 | zhangshan   |   26 |
|  6 | zhangshan   |   20 |
|  7 | lisi        | NULL |
|  8 | chenshuo    |   10 |
|  9 | wangwu      |    3 |
| 10 | qiuyi       |   15 |
| 11 | qiuxiaotian |   20 |
+----+-------------+------+
mysql> insert into student (id,name,age) values(1,'tom',20),(2,'jerry',23),(3,'wangqing',25),(4,'seann',28),(5,'zhangsan',26),(6,'zhangsan',20),(7,'lisi',null),(8,'chenshuo',10),(9,'wangwu',3),(10,'qiuyyi',15),(11,'qiuxiaotian',20);
Query OK, 11 rows affected (0.00 sec)
Records: 11  Duplicates: 0  Warnings: 0

mysql> select * from student;
+----+-------------+------+
| id | name        | age  |
+----+-------------+------+
|  1 | tom         |   20 |
|  2 | jerry       |   23 |
|  3 | wangqing    |   25 |
|  4 | seann       |   28 |
|  5 | zhangsan    |   26 |
|  6 | zhangsan    |   20 |
|  7 | lisi        | NULL |
|  8 | chenshuo    |   10 |
|  9 | wangwu      |    3 |
| 10 | qiuyyi      |   15 |
| 11 | qiuxiaotian |   20 |
+----+-------------+------+
11 rows in set (0.01 sec)

5.修改lisi的年齡為50

mysql> update student set age=50 where name='lisi';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> select * from student where name = 'lisi';
+----+------+------+
| id | name | age  |
+----+------+------+
|  7 | lisi |   50 |
+----+------+------+
1 row in set (0.00 sec)

6.以age欄位降序排序

mysql> select * from student order by age desc;
+----+-------------+------+
| id | name        | age  |
+----+-------------+------+
|  7 | lisi        |   50 |
|  4 | seann       |   28 |
|  5 | zhangsan    |   26 |
|  3 | wangqing    |   25 |
|  2 | jerry       |   23 |
|  1 | tom         |   20 |
|  6 | zhangsan    |   20 |
| 11 | qiuxiaotian |   20 |
| 10 | qiuyyi      |   15 |
|  8 | chenshuo    |   10 |
|  9 | wangwu      |    3 |
+----+-------------+------+
11 rows in set (0.00 sec)

7.查詢student表中年齡最小的3位同學跳過前2位

mysql> select * from student order by age  limit 2,3;
+----+-------------+------+
| id | name        | age  |
+----+-------------+------+
| 10 | qiuyyi      |   15 |
|  1 | tom         |   20 |
| 11 | qiuxiaotian |   20 |
+----+-------------+------+
3 rows in set (0.00 sec)

8.查詢student表中年齡最大的4位同學

mysql>  select * from student order by age desc limit 4;
+----+----------+------+
| id | name     | age  |
+----+----------+------+
|  7 | lisi     |   50 |
|  4 | seann    |   28 |
|  5 | zhangsan |   26 |
|  3 | wangqing |   25 |
+----+----------+------+
4 rows in set (0.00 sec)

9.查詢student表中名字叫zhangshan的記錄

mysql> select * from student where name = 'zhangsan' ;
+----+----------+------+
| id | name     | age  |
+----+----------+------+
|  5 | zhangsan |   26 |
|  6 | zhangsan |   20 |
+----+----------+------+
2 rows in set (0.00 sec)

10.查詢student表中名字叫zhangshan且年齡大於20歲的記錄

mysql> select * from student where name = 'zhangsan' and age >20;
+----+----------+------+
| id | name     | age  |
+----+----------+------+
|  5 | zhangsan |   26 |
+----+----------+------+
1 row in set (0.00 sec)

11.查詢student表中年齡在23到30之間的記錄

mysql> select * from student where age between 23 and 30;
+----+----------+------+
| id | name     | age  |
+----+----------+------+
|  2 | jerry    |   23 |
|  3 | wangqing |   25 |
|  4 | seann    |   28 |
|  5 | zhangsan |   26 |
+----+----------+------+
4 rows in set (0.00 sec)

12.修改wangwu的年齡為100

mysql> update student set age=100 where name = 'wangwu';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> select * from student where name ='wangwu';
+----+--------+------+
| id | name   | age  |
+----+--------+------+
|  9 | wangwu |  100 |
+----+--------+------+
1 row in set (0.00 sec)

13.刪除student中名字叫zhangshan且年齡小於等於20的記錄

mysql>  delete from student where name ='zhangsan'and age<=20;
Query OK, 1 row affected (0.00 sec)

mysql> select * from student where name = 'zhangsan' and age<=20;
Empty set (0.00 sec)
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