MySQL使用者端工具的使用與MySQL SQL語句

MySQL使用者端工具的使用

1、MySQL程式的組成

使用者端
- mysql:CLI互動式使用者端程式
- mycli:CLI互動式使用者端程式;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命令列工具
伺服器端
- mysqld

2、MySQL監聽地址

伺服器監聽的兩種socket地址：

socket型別	說明
ip socket	預設監聽在tcp的3306埠，支援遠端通訊
unix sock	監聽在sock檔案上(/tmp/mysql.sock,/var/lib/mysql/mysql.sock)僅支援本地通訊

3、資料庫組態檔

資料庫組態檔為：/etc/my.cnf和/etc/my.cnf.d目錄下的組態檔

//修改組態檔，設定字元編碼
[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、使用者端工具的使用

//語法：mysql [OPTIONS] [database]
//常用的OPTIONS：
    -uUSERNAME      //指定使用者名稱，預設為root
    -hHOST          //指定伺服器主機，預設為localhost，推薦使用ip地址
    -pPASSWORD      //指定使用者的密碼
    -P              //指定資料庫監聽的埠，如-P3307
    -S              //指定通訊端檔案位置，多範例部署MySQL時需要使用
    -V              //檢視當前使用的mysql版本
    -e              //不登入mysql執行sql語句後退出，常用於指令碼
    --defaults-file=組態檔	//指定MySQL組態檔位置，用於載入使用者端設定
    
[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，不推薦直接在命令列裡直接用-pPASSWORD的方式登入，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 資料型別

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

1、數值型別

MySQL 支援所有標準 SQL 數值資料型別。

這些型別包括嚴格數值資料型別(INTEGER、SMALLINT、DECIMAL 和 NUMERIC)，以及近似數值資料型別(FLOAT、REAL 和 DOUBLE PRECISION)。

型別	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、日期和時間型別

表示時間值的日期和時間型別為DATETIME、DATE、TIMESTAMP、TIME和YEAR。

每個時間型別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型別有專有的自動更新特性。

型別	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、字串型別

字串型別指CHAR、VARCHAR、BINARY、VARBINARY、BLOB、TEXT、ENUM和SET。

型別	大小	用途
CHAR	0-255 bytes	定長字串
VARCHAR	0-65535 bytes	變長字串
TINYBLOB	0-255 bytes	不超過 255 個字元的二進位制字串
TINYTEXT	0-255 bytes	短文字字串
BLOB	0-65 535 bytes	二進位制形式的長文字資料
TEXT	0-65 535 bytes	長文字資料
MEDIUMBLOB	0-16 777 215 bytes	二進位制形式的中等長度文字資料
MEDIUMTEXT	0-16 777 215 bytes	中等長度文字資料
LONGBLOB	0-4 294 967 295 bytes	二進位制形式的極大文字資料
LONGTEXT	0-4 294 967 295 bytes	極大文字資料

注意

char(n) 和 varchar(n) 中括號中 n 代表字元的個數，並不代表位元組個數，比如 CHAR(30) 就可以儲存 30 個字元。

CHAR 和 VARCHAR 型別類似，但它們儲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。在儲存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制字串而不要非二進位制字串。也就是說，它們包含位元組字串而不是字元字串。這說明它們沒有字元集，並且排序和比較基於列值位元組的數值值。

BLOB 是一個二進位制大物件，可以容納可變數量的資料。有 4 種 BLOB 型別：TINYBLOB、BLOB、MEDIUMBLOB 和 LONGBLOB。它們區別在於可容納儲存範圍不同。

有 4 種 TEXT 型別：TINYTEXT、TEXT、MEDIUMTEXT 和 LONGTEXT。對應的這 4 種 BLOB 型別，可儲存的最大長度不同，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

//建立資料庫
//語法：create database [if not exists] 'da_name';

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

//檢視當前範例有哪些資料庫
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)

//建立資料庫時,設定資料庫的字元集：
//character set:指定資料庫採用的字元集,utf8不能寫成utf-8,建議使用utf8mb4字元集
//collate:指定資料庫字元集的排序規則,utf8mb4的預設排序規則為utf8mb4_general_ci（通過show character set檢視）
mysql> create database dbtest character set utf8mb4 collate utf8mb4_general_ci;

//資料庫使用者端字元編碼需要和伺服器端字元集保持一致
//SET NAMES:指定使用者端字元集
mysql> SET NAMES utf8mb4;

//字元集設定都可寫入MySQL組態檔中啟動MySQL服務時自動載入

1.2 表DDL操作

//建立表
//語法：create table table_name (col1 datatype 修飾符,col2 datatype 修飾符) ENGINE='儲存引擎型別';

//在資料庫lsz裡建立表lsztable
mysql> CREATE DATABASE IF NOT EXISTS lsz;		//建立資料庫lsz
Query OK, 1 row affected (0.00 sec)

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

//建立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)

//檢視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)

//建立表時，設定欄位、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 使用者操作

MySQL使用者帳號由兩部分組成，如'USERNAME'@'HOST'，表示此USERNAME只能從此HOST上遠端登入；HOST用於限制此使用者可通過哪些主機遠端連線mysql程式。

HOST的值可為：

IP地址，如：172.16.12.129
萬用字元
- %：匹配任意長度的任意字元，常用於設定允許從任何主機登入
- _：匹配任意單個字元

//資料庫使用者建立
//語法：create user 'username'@'host' [identified by 'password'];

//建立資料庫使用者zsl
mysql> create user 'zsl'@'127.0.0.1' identified by 'Passwd123!';
Query OK, 0 rows affected (0.00 sec)

//使用新建立的使用者和密碼登入
[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> 

//刪除資料庫使用者
//語法：drop user 'username'@'host'; 

//刪除資料庫使用者zsl
mysql> drop user 'zsl'@'127.0.0.1';
Query OK, 0 rows affected (0.00 sec)

1.4 檢視命令show

mysql> show character set;		//檢視支援的所有字元集
+----------+---------------------------------+---------------------+--------+
| 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%';		//檢視使用者端的字元編碼
+--------------------------------------+----------------------------+
| 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;		//檢視某表中某欄位使用的字元編碼
......
......

mysql> show engines;		//檢視當前資料庫支援的所有儲存引擎
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| 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;		//檢視資料庫資訊
+--------------------+
| 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)

//檢視表結構
//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)

//檢視某表的建立命令，可以看到建立表時設定的引數
//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)

//檢視某表的狀態
//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

//修改資料庫字元集為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表新增新的一列，先檢視表結構
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表新增一列'phone'
mysql> alter table lsztable add phone int(11);
Query OK, 0 rows affected (0.02 sec)
Records: 0  Duplicates: 0  Warnings: 0

//檢視表結構
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;       //獲取建立表的幫助
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)，均屬針對表的操作。

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:

操作型別	常用操作符
操作符	>，<，>=，<=，=，!= BETWEEN column# AND column# LIKE：模糊匹配 RLIKE：基於正規表示式進行模式匹配 IS NOT NULL：非空 IS NULL：空
條件邏輯操作	AND OR NOT

ORDER BY：排序，預設為升序（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

#檢視表所有的內容
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)

#檢視表的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)

#檢視表中年齡大於等於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)

#檢視表中年齡大於等於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)

#檢視表中年齡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)

#檢視表中年齡不為空的
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)

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

#查詢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：

語句型別	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，並在事務紀錄檔中為所刪除的每行記錄一項可以通過回滾事務紀錄檔恢復資料非常佔用空間
truncate	刪除表中所有資料，且無法恢復表結構、約束和索引等保持不變，新新增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紀錄檔資源少通過釋放儲存表資料所用的資料頁來刪除資料，並且只在事務紀錄檔中記錄頁的釋放對於有外來鍵約束參照的表，不能使用TRUNCATE TABLE刪除資料不能用於加入了索引檢視的表

語句型別

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，並在事務紀錄檔中為所刪除的每行記錄一項可以通過回滾事務紀錄檔恢復資料非常佔用空間

truncate

刪除表中所有資料，且無法恢復表結構、約束和索引等保持不變，新新增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紀錄檔資源少通過釋放儲存表資料所用的資料頁來刪除資料，並且只在事務紀錄檔中記錄頁的釋放對於有外來鍵約束參照的表，不能使用TRUNCATE TABLE刪除資料不能用於加入了索引檢視的表

//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 建立授權grant

許可權型別(priv_type)

許可權型別	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

指定要操作的物件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：被授權的使用者可將自己的許可權副本轉贈給其他使用者，說白點就是將自己的許可權完全複製給另一個使用者。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使用者在資料庫本機上登入存取所有資料庫
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使用者在192.168.111.135上遠端登入存取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使用者在所有位置上遠端登入存取lsz資料庫
mysql> GRANT ALL ON lsz.* TO 'lsz'@'%' IDENTIFIED BY 'Passwd123!';
Query OK, 0 rows affected, 1 warning (0.00 sec)

//重新整理授權表
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

3.2 檢視授權

//檢視當前登入使用者的授權資訊
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)

//檢視指定使用者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服務程序啟動時會讀取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儲存於表中，mysql的服務程序會自動重讀授權表，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的服務程序重讀授權表

mysql> FLUSH PRIVILEGES;

實戰案例

1.搭建mysql服務

[root@localhost ~]# wget http://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.建立一個以你名字為名的資料庫，並建立一張表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.檢視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表中插入資料（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位元同學

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)