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)