25_MySQL存储引擎 数据导入导出 管理表记录 匹配条件

Posted 2021-03-12 luwei0915

版本：5.7.28
服务器：mysql 192.168.4.20

1.MySQL存储引擎的配置
查看服务支持的存储引擎
查看默认存储类型
更改表的存储引擎
设置数据库服务默认使用的存储引擎

查看存储引擎信息
mysql> SHOW ENGINES;
+--------------------+---------+-------------------
| Engine             | Support |
+--------------------+---------+---------------------
| InnoDB             | DEFAULT |
| MRG_MYISAM         | YES     |
| MEMORY             | YES     |
| BLACKHOLE          | YES     |
| MyISAM             | YES     |
| CSV                | YES     |
| ARCHIVE            | YES     |
| PERFORMANCE_SCHEMA | YES     |
| FEDERATED          | NO      |
+--------------------+---------+--------------------

查看默认存储类型
mysql> SHOW VARIABLES LIKE ‘default_storage_engine‘;
+------------------------+--------+
| Variable_name          | Value  |
+------------------------+--------+
| default_storage_engine | InnoDB |
+------------------------+--------+

修改默认存储引擎
指令修改
mysql> SET default_storage_engine=MyISAM;
mysql> SHOW VARIABLES LIKE ‘default_storage_engine‘;
+------------------------+--------+
| Variable_name          | Value  |
+------------------------+--------+
| default_storage_engine | MyISAM |
+------------------------+--------+
配置文件修改
]# vim /etc/my.cnf
...
default_storage_engine=MEMORY   //改用MEMORY引擎
]# systemctl restart mysqld.service
mysql> SHOW VARIABLES LIKE ‘default_storage_engine‘;
+------------------------+--------+
| Variable_name          | Value  |
+------------------------+--------+
| default_storage_engine | MEMORY |
+------------------------+--------+
 
2.数据导入、导出

2.1  将/etc/passwd文件导入MySQL数据库
新建userdb库、user表
mysql> CREATE DATABASE userdb;
mysql> USE userdb;
mysql> CREATE TABLE user(
    -> name varchar(24) NOT NULL,
    -> passwd varchar(48) DEFAULT ‘x‘,
    -> uid int(5) NOT NULL,
    -> gid int(5) NOT NULL,
    -> fullname varchar(128),
    -> homedir varchar(64) NOT NULL,
    -> shell varchar(24) NOT NULL
    -> );

mysql> DESC user;
+----------+--------------+------+-----+---------+-------+
| Field    | Type         | Null | Key | Default | Extra |
+----------+--------------+------+-----+---------+-------+
| name     | varchar(24)  | NO   |     | NULL    |       |
| passwd   | varchar(48)  | YES  |     | x       |       |
| uid      | int(5)       | NO   |     | NULL    |       |
| gid      | int(5)       | NO   |     | NULL    |       |
| fullname | varchar(128) | YES  |     | NULL    |       |
| homedir  | varchar(64)  | NO   |     | NULL    |       |
| shell    | varchar(24)  | NO   |     | NULL    |       |
+----------+--------------+------+-----+---------+-------+

查看mysql的工作文件夹
mysql> SHOW VARIABLES LIKE ‘%secure_file_priv‘;
+------------------+-----------------------+
| Variable_name    | Value                 |
+------------------+-----------------------+
| secure_file_priv | /var/lib/mysql-files/ |
+------------------+-----------------------+
在MySQL 5.7.6版本之后，导入文件只能在secure_file_priv指定的文件夹下。
 
拷贝数据到目录
mysql> system cp /etc/passwd /var/lib/mysql-files/
mysql> LOAD DATA INFILE ‘/var/lib/mysql-files/passwd‘
    -> INTO TABLE user
    -> FIELDS TERMINATED BY ‘:‘
    -> LINES TERMINATED BY ‘ ‘;(这条默认有，除非用其他分隔用）

mysql> SELECT COUNT(*) FROM user;
+----------+
| COUNT(*) |
+----------+
|       24 |
+----------+

查看user前5条记录，列出用户名、UID
mysql> SELECT name ,uid FROM user LIMIT 5;
+--------+-----+
| name   | uid |
+--------+-----+
| root   |   0 |
| bin    |   1 |
| daemon |   2 |
| adm    |   3 |
| lp     |   4 |
+--------+-----+
 
为user表中的每条记录添加自动编号
mysql> ALTER TABLE user ADD sn int(4) AUTO_INCREMENT PRIMARY KEY FIRST;
mysql> SELECT sn,name FROM user LIMIT 5;
+----+--------+
| sn | name   |
+----+--------+
|  1 | root   |
|  2 | bin    |
|  3 | daemon |
|  4 | adm    |
|  5 | lp     |
+----+--------+
 
2.2 从MySQL数据库中导出查询结果
以将userdb库user表中UID大于100的前10条记录导出

安全导出
mysql> SELECT * FROM user WHERE uid>100 LIMIT 10 into outfile ‘/var/lib/mysql-files/test.txt‘;

以将userdb库user表中UID大于100的前10条记录导出为/myload/user1.txt
修改默认目录
]# ls -ld /var/lib/mysql-files/
drwxr-x--- 2 mysql mysql 36 2月   3 10:29 /var/lib/mysql-files/
]# mkdir /myload
]# chown mysql /myload
]# ls -ld /myload
drwxr-xr-x 2 mysql root 6 2月   3 10:32 /myload
# vim /etc/my.cnf
[mysqld]
...
secure_file_priv="/myload"
]# systemctl restart mysqld
mysql> SHOW VARIABLES LIKE ‘secure_file_priv‘;
+------------------+----------+
| Variable_name    | Value    |
+------------------+----------+
| secure_file_priv | /myload/ |
+------------------+----------+

导出user表中UID小于5的记录
如果以默认的‘ ‘ 为行分隔，导出操作同样可不指定LINES TERMINATED BY：
mysql> SELECT * FROM userdb.user WHERE uid<5;
+--------+--------+-----+-----+----------+----------------+---------------+
| name   | passwd | uid | gid | fullname | homedir        | shell         |
+--------+--------+-----+-----+----------+----------------+---------------+
| root   | x      |   0 |   0 | root     | /root          | /bin/bash     |
| bin    | x      |   1 |   1 | bin      | /bin           | /sbin/nologin |
| daemon | x      |   2 |   2 | daemon   | /sbin          | /sbin/nologin |
| adm    | x      |   3 |   4 | adm      | /var/adm       | /sbin/nologin |
| lp     | x      |   4 |   7 | lp       | /var/spool/lpd | /sbin/nologin |
+--------+--------+-----+-----+----------+----------------+---------------+
导出：
mysql> SELECT * FROM userdb.user WHERE uid<5
    -> INTO OUTFILE ‘/myload/user1.txt‘
    -> FIELDS TERMINATED BY ‘:‘;
]# wc -l /myload/user1.txt
5 /myload/user1.txt
 
3.操作表记录
表记录的插入
表记录的更新
表记录的查询
表记录的删除
 
3.1 删除表的所有记录
mysql> DELETE FROM user;
mysql> SELECT * FROM user;
 
3.2 给t1插入三条数据
mysql> CREATE TABLE t1(
    -> name varchar(10),
    -> sex enum("boy","girl"),
    -> age int(3)
    -> );

mysql> INSERT t1 VALUES
    -> (‘Jim‘,‘girl‘,24),
    -> (‘Tom‘,‘boy‘,21),
    -> (‘Lily‘,‘girl‘,20);

mysql> SELECT * FROM t1;
+------+------+------+
| name | sex  | age  |
+------+------+------+
| Jim  | girl |   24 |
| Tom  | boy  |   21 |
| Lily | girl |   20 |
+------+------+------+
 
3.3 只插入部分字段的值
mysql> INSERT INTO t1(name,age)
    -> VALUES(‘Jerry‘,27);

3.3 更新表记录时，若未限制条件，则适用于所有记录
mysql> UPDATE t1 SET age=10;
则所有人年龄都是10
 
3.4 更新表记录时，可以限制条件，只对符合条件的记录有效
mysql> UPDATE t1 SET age=20
    -> WHERE sex=‘boy‘;
 
3.5 删除表记录时，可以限制条件，只删除符合条件的记录
mysql> DELETE FROM t1 WHERE age < 18;
 
3.6 删除表记录时，如果未限制条件，则会删除所有的表记录
mysql> DELETE FROM t1;
 

4.查询及匹配条件
mysql> SELECT * FROM stu_info;
+------+------+------+
| name | sex  | age  |
+------+------+------+
| Jim  | girl |   24 |
| Tom  | boy  |   21 |
| Lily | girl |   20 |
+------+------+------+

4.1 查询stu_info表一共有多少条记录
mysql> SELECT count(*) FROM stu_info;
+----------+
| count(*) |
+----------+
|        3 |
+----------+

4.2 计算stu_info表中各学员的平均年龄、最大年龄、最小年龄
mysql> SELECT avg(age),max(age),min(age) FROM stu_info;
+----------+----------+----------+
| avg(age) | max(age) | min(age) |
+----------+----------+----------+
|  21.6667 |       24 |       20 |
+----------+----------+----------+

4.3 计算stu_info表中男学员的个数
mysql> SELECT count(sex) FROM stu_info WHERE sex=‘boy‘;
+------------+
| count(sex) |
+------------+
|          1 |
+------------+

4.4 列出stu_info表中年龄为21岁的学员记录
mysql> SELECT * FROM stu_info WHERE age=21;
 
4.5 列出stu_info表中年龄超过21岁的学员记录
mysql> SELECT * FROM stu_info WHERE age>21;
 
4.6 列出stu_info表中年龄大于或等于21岁的学员记录
mysql> SELECT * FROM stu_info WHERE age>=21;
 
4.7 列出stu_info表中年龄在20岁和24岁之间的学员记录
mysql> SELECT * FROM stu_info WHERE age BETWEEN 20 and 24;
 
4.8 列出stu_info表中年龄小于23岁的女学员记录
mysql> SELECT * FROM stu_info WHERE age < 23 AND sex=‘girl‘;
 
4.9 列出stu_info表中年龄小于23岁的学员，或者女学员的记录
mysql> SELECT * FROM stu_info WHERE age < 23 OR sex=‘girl‘;
 
4.10 如果某个记录的姓名属于指定范围内的一个，则将其列出
mysql> SELECT * FROM stu_info WHERE name IN
    -> (‘Jim‘,‘Tom‘,‘Mickey‘,‘Minnie‘);
 
4.11 计算1234与5678的和
mysql> SELECT 1234+5678;
+-----------+
| 1234+5678 |
+-----------+
|      6912 |
+-----------+

4.12 输出stu_info表各学员的姓名、15年后的年龄
mysql> SELECT name,age+15 FROM stu_info;
+------+--------+
| name | age+15 |
+------+--------+
| Jim  |     39 |
| Tom  |     36 |
| Lily |     35 |
+------+--------+
 
4.13 列出stu_info表中姓名以“J”开头的学员记录
mysql> SELECT * FROM stu_info WHERE name LIKE ‘J%‘;
 
4.14 列出stu_info表中姓名以“J”开头且只有3个字母的学员记录
mysql> SELECT * FROM stu_info WHERE name LIKE ‘J__‘;
 
4.15 列出stu_info表中姓名以“J”开头且以“y”结尾的学员记录
mysql> SELECT * FROM stu_info WHERE name REGEXP ‘^J.*y$‘;
效果等同于：
mysql> SELECT * FROM stu_info WHERE name Like ‘J%y‘;
 
4.16 列出stu_info表中姓名以“J”开头或者以“y”结尾的学员记录：
mysql> SELECT * FROM stu_info WHERE name REGEXP ‘^J|y$‘;
效果等同于：
mysql> SELECT * FROM stu_info WHERE name Like ‘J%‘ OR name Like ‘%y‘;
 
4.17 列出stu_info表的所有记录，按年龄排序
mysql> SHOW SESSION VARIABLES;
mysql> SHOW SESSION VARIABLES;
mysql> select @@sql_mode;
+-------------------------------------------------------------------------------------------------------------------------------------------+
| @@sql_mode                                                                                                                                |
+-------------------------------------------------------------------------------------------------------------------------------------------+
| ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION |
+-------------------------------------------------------------------------------------------------------------------------------------------+

说明：如果启用了only_full_group_by SQL模式(在默认情况下是这样)，那么MySQL就会拒绝选择列表、条件或顺序列表引用的查询，这些查询将引用组中未命名的非聚合列，而不是在功能上依赖于它们。(在5.7.5之前，MySQL没有检测到功能依赖项，only_full_group_by在默认情况下是不启用的。

执行以下命令：
mysql> set global sql_mode=‘STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION‘;
mysql> set session sql_mode=‘STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION‘;
这两个命令，去掉 sql_mode 的 ONLY_FULL_GROUP_BY

现在执行
mysql> SELECT * FROM stu_info GROUP BY age;(ASC,由小到大,默认)
+------+------+------+
| name | sex  | age  |
+------+------+------+
| Lily | girl |   20 |
| Tom  | boy  |   21 |
| Jim  | girl |   24 |
+------+------+------+

mysql> SELECT * FROM stu_info GROUP BY age DESC;(由大到小）
+------+------+------+
| name | sex  | age  |
+------+------+------+
| Jim  | girl |   24 |
| Tom  | boy  |   21 |
| Lily | girl |   20 |
+------+------+------+
 
4.18 限制查询结果的输出条数，LIMIT
mysql> SELECT * FROM stu_info LIMIT 2;
 
4.19 列出stu_info表中年龄最小的2条学员记录由小到大输出
mysql> SELECT * FROM stu_info GROUP BY age ASC LIMIT 2;
+------+------+------+
| name | sex  | age  |
+------+------+------+
| Lily | girl |   20 |
| Tom  | boy  |   21 |
+------+------+------+
 
4.20 分组查询结果，GROUP BY
针对stu_info表，按性别分组，分别统计出男、女学员的人数：
mysql> SELECT sex,count(sex) FROM stu_info GROUP BY sex;
+------+------------+
| sex  | count(sex) |
+------+------------+
| boy  |          1 |
| girl |          2 |
+------+------------+

列出查询字段时，可以通过AS关键字来指定显示别名，比如上述操作可改为：
mysql> SELECT sex AS ‘性别‘,count(sex) AS ‘人数‘
    -> FROM stu_info GROUP BY sex;
+--------+--------+
| 性别   | 人数   |
+--------+--------+
| boy    |      1 |
| girl   |      2 |
+--------+--------+