MySQL是一款常用的關(guān)系型數(shù)據(jù)庫管理系統(tǒng),廣泛應(yīng)用于各個領(lǐng)域。在使用MySQL時,我們經(jīng)常需要編寫一些常用腳本來進行數(shù)據(jù)操作和管理。本文將介紹一些常用的MySQL腳本,幫助更好地使用MySQL。
一、啟停MySQL數(shù)據(jù)庫服務(wù)
- 啟動MySQL數(shù)據(jù)庫服務(wù)
systemctl start mysqld
- 停止MySQL數(shù)據(jù)庫服務(wù)
systemctl stop mysqld
- MySQL數(shù)據(jù)庫服務(wù)狀態(tài)查看
systemctl status mysqld
- MySQL數(shù)據(jù)庫服務(wù)開機自啟
systemctl enable mysqld
- MySQL數(shù)據(jù)庫服務(wù)禁止開機自啟
systemctl disable mysqld
二、連接MySQL數(shù)據(jù)庫
在使用MySQL之前,我們需要先連接到數(shù)據(jù)庫??梢允褂靡韵履_本進行連接:
- 使用用戶名和密碼連接MySQL數(shù)據(jù)庫
mysql -u username -p password
或者
mysql -u username -p
其中,username為數(shù)據(jù)庫用戶名,password為數(shù)據(jù)庫密碼。
- 使用主機名、用戶名和密碼連接MySQL數(shù)據(jù)庫
mysql -h 主機名 -P 端口號 -u 用戶名 -p 密碼
或者
mysql -h 主機名 -P 端口號 -u 用戶名 -p
- 使用數(shù)據(jù)庫
連接到 MySQL 數(shù)據(jù)庫后,可能有多個可以操作的數(shù)據(jù)庫,可使用use 命令選擇你要操作的數(shù)據(jù)庫。
use 數(shù)據(jù)庫名;
- 關(guān)閉MySQL數(shù)據(jù)庫連接的SQL語句
exit;
或者
quit;
三、創(chuàng)建和管理數(shù)據(jù)庫
- 創(chuàng)建數(shù)據(jù)庫:使用CREATE DATABASE語句可以創(chuàng)建新的數(shù)據(jù)庫(mydatabase),例如:
mysql> CREATE DATABASE mydatabase;
Query OK, 1 row affected (0.00 sec)
mysql>
- 刪除數(shù)據(jù)庫(慎用):使用DROP DATABASE語句可以刪除指定的數(shù)據(jù)庫(mydatabase),例如:
mysql> DROP DATABASE mydatabase;
Query OK, 0 rows affected (0.01 sec)
mysql>
- 查看數(shù)據(jù)庫:使用SHOW DATABASES語句可以列出當前所有的數(shù)據(jù)庫,例如:
mysql> SHOW DATABASES;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mydatabase |
| mysql |
| performance_schema |
| sys |
+--------------------+
5 rows in set (0.00 sec)
mysql>
- 查看當前使用的數(shù)據(jù)庫:
mysql> select database();
+------------+
| database() |
+------------+
| mydatabase |
+------------+
1 row in set (0.00 sec)
mysql>
- 查看當前數(shù)據(jù)庫包含的表信息
mysql> show tables;
+----------------------+
| Tables_in_mydatabase |
+----------------------+
| users |
+----------------------+
1 row in set (0.00 sec)
mysql>
- 獲取表結(jié)構(gòu)
mysql> desc users;
+-------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+----------------+
| id | int | NO | PRI | NULL | auto_increment |
| name | varchar(50) | YES | | NULL | |
| age | int | YES | | NULL | |
| email | varchar(50) | YES | | NULL | |
+-------+-------------+------+-----+---------+----------------+
4 rows in set (0.00 sec)
mysql>
- 查看數(shù)據(jù)庫版本
mysql> select version();
+-----------+
| version() |
+-----------+
| 8.0.32 |
+-----------+
1 row in set (0.00 sec)
mysql>
四、創(chuàng)建和管理數(shù)據(jù)表
- 創(chuàng)建數(shù)據(jù)表
數(shù)據(jù)表是數(shù)據(jù)庫中存儲數(shù)據(jù)的主要方式??梢允褂靡韵履_本創(chuàng)建一個名為users
的數(shù)據(jù)表:
mysql> use mydatabase
Database changed
mysql>
mysql> CREATE TABLE users (
-> id INT AUTO_INCREMENT PRIMARY KEY,
-> name VARCHAR(50),
-> age INT,
-> email VARCHAR(50)
-> );
Query OK, 0 rows affected (0.01 sec)
mysql>
- 插入數(shù)據(jù)
插入數(shù)據(jù)是將數(shù)據(jù)添加到數(shù)據(jù)庫中的關(guān)鍵操作??梢允褂靡韵履_本向users
表中插入一條數(shù)據(jù):
mysql> INSERT INTO users (name, age, email) VALUES ('John', 25, 'john@example.com');
Query OK, 1 row affected (0.01 sec)
mysql>
- 查詢數(shù)據(jù)
查詢數(shù)據(jù)是使用MySQL的常見操作之一??梢允褂靡韵履_本查詢users
表中的所有數(shù)據(jù):
mysql> SELECT * FROM users;
+----+------+------+------------------+
| id | name | age | email |
+----+------+------+------------------+
| 1 | John | 25 | john@example.com |
+----+------+------+------------------+
1 row in set (0.00 sec)
mysql>
- 更新數(shù)據(jù)
更新數(shù)據(jù)是在數(shù)據(jù)庫中修改現(xiàn)有數(shù)據(jù)的操作??梢允褂靡韵履_本將users
表中id
為1的記錄的age
字段更新為30:
mysql> UPDATE users SET age = 30 WHERE id = 1;
Query OK, 1 row affected (0.01 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> SELECT * FROM users;
+----+------+------+------------------+
| id | name | age | email |
+----+------+------+------------------+
| 1 | John | 30 | john@example.com |
+----+------+------+------------------+
1 row in set (0.00 sec)
mysql>
- 刪除數(shù)據(jù)
刪除數(shù)據(jù)是從數(shù)據(jù)庫中刪除不再需要的數(shù)據(jù)的操作。可以使用以下腳本刪除users
表中id
為1的記錄:
DELETE FROM users WHERE id = 1;
- 排序數(shù)據(jù):使用ORDER BY子句可以對查詢結(jié)果進行排序。以下是按照年齡從小到大對"users"表中的記錄進行排序的示例:
SELECT * FROM users ORDER BY age ASC;
- 連接表:使用JOIN語句可以將多個表連接起來進行查詢。以下是連接"users"表和"orders"表,并檢索用戶和訂單信息的示例:
SELECT users.name, orders.order_number FROM users JOIN orders ON users.id = orders.user_id;
- 創(chuàng)建索引:使用CREATE INDEX語句可以為表中的列創(chuàng)建索引,以提高查詢效率。以下是為"users"表中的name列創(chuàng)建索引的示例:
CREATE INDEX idx_name ON users (name);
- 刪除表和數(shù)據(jù)庫(慎用):使用DROP TABLE語句可以刪除表,使用DROP DATABASE語句可以刪除數(shù)據(jù)庫。以下是刪除"users"表和"mydatabase"數(shù)據(jù)庫的示例:
DROP TABLE users;
DROP DATABASE mydatabase;
- 更改表名
rename table 原表名 to 新表名;
mysql> rename table users to t_users;
Query OK, 0 rows affected (0.01 sec)
mysql> select * from t_users;
+----+------+------+-------------------+
| id | name | age | email |
+----+------+------+-------------------+
| 1 | John | 30 | john.com
|2 | Tom | 25 | tom.com
|3 | Zyl | 18 | zyl.com
+----+------+------+-------------------+
3 rows in set (0.00 sec)
mysql>
- mysql的表中增加字段
###表t_users 中添加了一個字段address ,類型為 varchar(255)。
mysql> alter table t_users add column address varchar(255);
Query OK, 0 rows affected (0.01 sec)
- 授權(quán)
MySQL8.0 以上將創(chuàng)建賬戶和賦予權(quán)限分開了,需要用兩個語句創(chuàng)建賬號,賦予遠程權(quán)限;
###1、創(chuàng)建test用戶
create user 'test'@'%' identified by 'Test##2023';
###授權(quán)所有權(quán)限
grant all privileges on *.* to 'test'@'%' with grant option;
###部分權(quán)限(select, insert),這個用戶只能連接到數(shù)據(jù)庫,并擁有select, insert權(quán)限。
mysql> grant select, insert on mydatabase.* to 'test'@'%' with grant option;
Query OK, 0 rows affected (0.01 sec)
mysql>
###驗證test用戶權(quán)限
mysql> show grants for 'test'@'%';
mysql> delete from t_users;
ERROR 1142 (42000): DELETE command denied to user 'test'@'localhost' for table 't_users'
mysql>
###---->該用戶目前沒有DELETE 的權(quán)限
五、數(shù)據(jù)備份和恢復(fù)
備份數(shù)據(jù)庫:使用mysqldump命令可以備份整個數(shù)據(jù)庫,例如:
mysqldump -u username -p mydatabase > backup.sql
[root-server ~]# mysqldump -u root -p mydatabase > backup.sql
Enter password:
[root-server ~]# ll
total 1964180
-rw-r--r--. 1 root root 2036 Jul 29 17:35 backup.sql
恢復(fù)數(shù)據(jù)庫:使用mysql命令可以從備份文件中恢復(fù)數(shù)據(jù)庫,例如:
mysql -u username -p mydatabase < backup.sql
###刪除表數(shù)據(jù)
mysql> delete from users;
Query OK, 3 rows affected (0.02 sec)
###恢復(fù)
[root-server ~]# mysql -u root -p mydatabase < backup.sql
Enter password:
[root-server ~]#
###驗證
mysql> select * from users;
+----+------+------+-------------------+
| id | name | age | email |
+----+------+------+-------------------+
| 1 | John | 30 | john.com
|2 | Tom | 25 | tom.com
|3 | Zyl | 18 | zyl.com
+----+------+------+-------------------+
3 rows in set (0.00 sec)
mysql>
導出數(shù)據(jù)到csv文件:
###創(chuàng)建目錄、賦權(quán)
[root-server ~]# mkdir -p /path/to
[root-server ~]# chmod -R 777 /path/to/
[root-server ~]# cd /path/
[root-server path]# ll
total 0
drwxrwxrwx. 2 root root 6 Jul 29 17:20 to
[root-server path]#
配置 secure_file_priv 變量,在/etc/my.cnf文件中加入
secure_file_priv=/path/to
重啟數(shù)據(jù)庫服務(wù):
systemctl restart mysqld
導出數(shù)據(jù)是將數(shù)據(jù)庫中的數(shù)據(jù)導出到文件的操作??梢允褂靡韵履_本將users
表中的數(shù)據(jù)導出到users.csv
文件中:
mysql> SELECT * INTO OUTFILE '/path/to/users.csv' FIELDS TERMINATED BY ',' LINES TERMINATED BY '\n' FROM users;
Query OK, 1 row affected (0.00 sec)
mysql>
從csv文件導入數(shù)據(jù):
導入數(shù)據(jù)是將文件中的數(shù)據(jù)導入到數(shù)據(jù)庫中的操作??梢允褂靡韵履_本將users.csv
文件中的數(shù)據(jù)導入到users
表中:
mysql> LOAD DATA INFILE '/path/to/users.csv' INTO TABLE users FIELDS TERMINATED BY ',' LINES TERMINATED BY '\n';
Query OK, 3 rows affected (0.01 sec)
Records: 3 Deleted: 0 Skipped: 0 Warnings: 0
mysql>
導出數(shù)據(jù)到txt文件:
使用SELECT INTO OUTFILE語句可以將查詢結(jié)果導出為文件,例如:
mysql> SELECT * INTO OUTFILE '/path/to/result.txt' FROM users;
Query OK, 3 rows affected (0.01 sec)
mysql>
從txt文件導入導入數(shù)據(jù):
使用LOAD DATA INFILE語句可以將數(shù)據(jù)從文件導入到表中,例如:
LOAD DATA INFILE '/path/to/result.txt' INTO TABLE users;
導出一個表:
mysqldump -u 用戶名 -p 數(shù)據(jù)庫名 表名> 導出的文件名
[root-server ~]# mysqldump -u root -p mydatabase users > mydatabases_users.sql
Enter password:
[root-server ~]# ll
total 1964184
-rw-r--r--. 1 root root 2036 Jul 29 18:07 mydatabases_users.sql
導出一個數(shù)據(jù)庫結(jié)構(gòu):
###參數(shù): -d 沒有數(shù)據(jù) --add-drop-table 在每個create語句之前增加一個drop table
[root-server ~]# mysqldump -u root -p -d --add-drop-table mydatabase > mydatabase-tab.sql
Enter password:
[root-server ~]# ll
total 1964196
-rw-r--r--. 1 root root 2036 Jul 29 17:35 backup.sql
-rw-r--r--. 1 root root 2036 Jul 29 18:07 mydatabases_users.sql
-rw-r--r--. 1 root root 1732 Jul 29 18:12 mydatabase-tab.sql
source 命令導入數(shù)據(jù):
mysql> delete from users;
Query OK, 3 rows affected (0.00 sec)
####備份文件位置
mysql> source /root/backup.sql
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.01 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected, 1 warning (0.01 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 3 rows affected (0.01 sec)
Records: 3 Duplicates: 0 Warnings: 0
Query OK, 0 rows affected (0.04 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
mysql>
###驗證:
mysql> select * from users;
+----+------+------+-------------------+
| id | name | age | email |
+----+------+------+-------------------+
| 1 | John | 30 | john.com
|2 | Tom | 25 | tom.com
|3 | Zyl | 18 | zyl.com
+----+------+------+-------------------+
3 rows in set (0.00 sec)
mysql>
注意:
mysqldump導出mysql數(shù)據(jù)庫中某個數(shù)據(jù)庫的數(shù)據(jù),用mysqldump只要把輸出符號換為輸入符號。那樣導入后,雖說不報錯,但是數(shù)據(jù)庫中是沒有任何數(shù)據(jù)的!需要直接通過mysql命令來實現(xiàn)。
恢復(fù)數(shù)據(jù)庫:使用mysql命令可以從備份文件中恢復(fù)數(shù)據(jù)庫,例如:
mysql -u username -p mydatabase < backup.sql
###刪除表數(shù)據(jù)
mysql> delete from users;
Query OK, 3 rows affected (0.02 sec)
###恢復(fù)
[root-server ~]# mysql -u root -p mydatabase < backup.sql
Enter password:
[root-server ~]#
###驗證
mysql> select * from users;
+----+------+------+-------------------+
| id | name | age | email |
+----+------+------+-------------------+
| 1 | John | 30 | john.com
|2 | Tom | 25 | tom.com
|3 | Zyl | 18 | zyl.com
+----+------+------+-------------------+
3 rows in set (0.00 sec)
mysql>
六、查詢與優(yōu)化
查詢數(shù)據(jù):使用SELECT語句可以從表中查詢數(shù)據(jù),例如:文章來源:http://www.zghlxwxcb.cn/news/detail-617529.html
mysql> SELECT * FROM users WHERE id = 1;
+----+------+------+-------------------+
| id | name | age | email |
+----+------+------+-------------------+
| 1 | John | 30 | john@example.com
+----+------+------+-------------------+
1 row in set (0.00 sec)
mysql>
優(yōu)化查詢:使用EXPLAIN語句可以分析查詢語句的執(zhí)行計劃,例如:文章來源地址http://www.zghlxwxcb.cn/news/detail-617529.html
mysql> EXPLAIN SELECT * FROM users WHERE id = 1;
+----+-------------+-------+------------+-------+---------------+---------+---------+-------+------+----------+-------+
| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+----+-------------+-------+------------+-------+---------------+---------+---------+-------+------+----------+-------+
| 1 | SIMPLE | users | NULL | const | PRIMARY | PRIMARY | 4 | const | 1 | 100.00 | NULL |
+----+-------------+-------+------------+-------+---------------+---------+---------+-------+------+----------+-------+
1 row in set, 1 warning (0.00 sec)
mysql>
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