mysql-linux-3

上午：
MySQL存储引擎
作为可插拔的组件提供
-mysql服务软件自带的功能程序，处理表的处理器
-不同的存储引擎有不同的功能和数据存储方式
默认的存储引擎
MYSQL 5.0/5.1 ----MyISAM
MySQL 5.5/5.6 ----InnoDB
mysql-5.7.17社区开源板
mysql> show engines;
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| 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)

查看表使用的存储引擎
mysql> show create table t32;
+-------+--------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+--------------------------------------------------------------------------------------------+
| t32 | CREATE TABLE `t32` (
`name` char(10) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-------+--------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

建表时指定表使用的存储引擎
mysql> create table t32(name char(10))engine=myisam;
Query OK, 0 rows affected (0.32 sec)

mysql> show create table t32;
+-------+--------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+--------------------------------------------------------------------------------------------+
| t32 | CREATE TABLE `t32` (
`name` char(10) DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 |
+-------+--------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

修改表使用的存储引擎

mysql> alter table t32 engine=InnoDB
-> ;
Query OK, 0 rows affected (0.28 sec)
Records: 0 Duplicates: 0 Warnings: 0

mysql> show create table t32;
+-------+--------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+--------------------------------------------------------------------------------------------+
| t32 | CREATE TABLE `t32` (
`name` char(10) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-------+--------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

查看数据库服务使用的存储引擎
mysql> show engines;
建表时指定使用的存储引擎
mysql> create table t32(name char(10))engine=myisam;
Query OK, 0 rows affected (0.32 sec)
修改数据库服务软件默认使用的存储引擎
[root@localhost ~]# cat /etc/my.cnf
default-storage-engine=myisam
[root@localhost ~]# systemctl stop mysqld
[root@localhost ~]# systemctl start mysqld
mysql> show engines;
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| Engine | Support | Comment | Transactions | XA | Savepoints |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| InnoDB | YES | 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 | DEFAULT | 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> use db1;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> create table t34(age int);
Query OK, 0 rows affected (0.19 sec)

mysql> use db1;
Database changed
mysql> show create table t34;
+-------+------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+------------------------------------------------------------------------------------------+
| t34 | CREATE TABLE `t34` (
`age` int(11) DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 |
+-------+------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
工作中怎么选用存储引擎

常用存储引擎特点
myisam
不支持事务、事务回滚、外键
支持表级锁
存储方式：一个表对应3个存储文件
表名.frm 表结构
表名.MYD 数据
表名.NYI 索引
事务：对数据库服务的访问过程（连接数据库服务器、操作数据、断开连接）
支持事务的表有对应的事务日志文件记录执行过的SQL操作
事务特性：原子性（操作要么成功要么失败），一致性（操作没有完成，表中的记录是没有变化的），隔离性（操作隔离），持久性（数据提交则数据永久改变）
ib_buffer_pool
ibdata1
ib_logfile0

事务回滚：在事务执行过程中，任何一步操作失败，都会恢复之前的所有操作
mysql> create table t36(id int)engine=innodb;
Query OK, 0 rows affected (0.23 sec)

mysql> insert into t36 values(100);
Query OK, 1 row affected (0.07 sec)

mysql> select *from t36;
+------+
| id |
+------+
| 100 |
+------+
1 row in set (0.00 sec)

mysql> show variables like "autocommit";
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| autocommit | ON |
+---------------+-------+
1 row in set (0.01 sec)

mysql> set autocommit=off;
Query OK, 0 rows affected (0.00 sec)

mysql> show variables like "autocommit";
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| autocommit | OFF |
+---------------+-------+
1 row in set (0.00 sec)

mysql> delete form t36;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 't36' at line 1
mysql> delete from t36;
Query OK, 1 row affected (0.00 sec)

mysql> select * from t36;
Empty set (0.00 sec)

mysql> roolback
-> ;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'roolback' at line 1
mysql> rollback;
Query OK, 0 rows affected (0.05 sec)

mysql> select * from t36;
+------+
| id |
+------+
| 100 |
+------+
1 row in set (0.00 sec)

mysql> commit
-> ;
Query OK, 0 rows affected (0.00 sec)

mysql> select * from t36;
+------+
| id |
+------+
| 100 |
+------+
1 row in set (0.00 sec)

mysql> set autocommit=ON;
Query OK, 0 rows affected (0.00 sec)

innodb
支持事务、事务回滚、行级锁、外键
存储方式：一个表对应2个存储文件
表名.frm 表结构
表名.ibd 数据和索引
锁粒度：
行级锁 innodb 只给当前被访问的行加锁，没有被访问的不加锁i
表级锁 myisam 只要对表做访问无论访问1行还是10行都回把整张表锁上

锁：解决的是并发访问冲突访问。
根据客户端的访问类型，锁又分为
读锁共享锁 select
写锁排他锁互斥锁 insert update delete
建表是根据存储引擎的特点决定表使用那种存储引擎
写操作多的表适合使用innodb存储引擎，此引擎支持行级锁，这样对表的并发访问量大。
查询操作多的表适合使用myisam存储引擎，此引擎支持表级锁，只锁一次这样可以节省系统资源。

二。数据导入导出（批量操作数据）
2.1 数据导入的命令格式及数据导入时的注意事项
导入数据的命令格式：
数据导入：把系统文件的内容存储到数据昆服务器的表里。
把系统已有用户的信息保存到db3库下的usertab表里。

导入数据
1.把需要导入的数据放入到相应的文件夹中
mysql> show variables like "secure_file_priv";
+------------------+-----------------------+
| Variable_name | Value |
+------------------+-----------------------+
| secure_file_priv | /var/lib/mysql-files/ |
+------------------+-----------------------+
1 row in set (0.00 sec)
[root@localhost lib]# cd mysql-files/
[root@localhost mysql-files]# ls
[root@localhost mysql-files]# cp /etc/passwd /var/lib/mysql-files/
2.导入数据
mysql> load data
-> infile "/var/lib/mysql-files/passwd"
-> into table user1
-> fields terminated by ":"
-> lines terminated by "\n";
Query OK, 41 rows affected (0.00 sec)
Records: 41 Deleted: 0 Skipped: 0 Warnings: 0
mysql> alter table user1
-> add
-> id int(2) primary key auto_increment first;
Query OK, 41 rows affected (0.06 sec)
Records: 41 Duplicates: 0 Warnings: 0

下午课程：
3.更改指定的导入的路茎
[root@localhost ~]# mkdir /mydata
[root@localhost ~]# chown mysql /mydata/
[root@localhost ~]# ls -ld /mydata/
drwxr-xr-x. 2 mysql root 6 6月 27 10:37 /mydata/
[root@localhost ~]# gentenforce
bash: gentenforce: 未找到命令...
[root@localhost ~]# getenforce
Permissive
[root@localhost ~]# vim /etc/my.cnf
[mysqld]
secure_file_priv="/mydata"
[root@localhost ~]# systemctl stop mysqld
[root@localhost ~]# systemctl start mysqld
mysql> show variables like "secure_file_priv";
+------------------+----------+
| Variable_name | Value |
+------------------+----------+
| secure_file_priv | /mydata/ |
+------------------+----------+
1 row in set (0.00 sec)

数据导出
mysql> select * from user1 into outfile
-> "/mydata/user.txt";
Query OK, 123 rows affected (0.00 sec)
mysql> select name from user1 into outfile "/mydata/user3.txt";
Query OK, 123 rows affected (0.00 sec)
[root@localhost mydata]# ls
passwd user2.txt user3.txt user.txt
在导出的数据的行和列加相应的间隔符号
mysql> select * from user1 into outfile "/mydata/user9\.txt" fields terminated by ":" lines terminated by "\n";
Query OK, 123 rows affected (0.00 sec)

管理表记录
mysql> desc user1;
+----------+-----------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+-----------+------+-----+---------+-------+
| name | char(30) | YES | MUL | NULL | |
| password | char(1) | YES | | NULL | |
| uid | int(11) | YES | | NULL | |
| gid | int(11) | YES | | NULL | |
| comment | char(100) | YES | | NULL | |
| homefir | char(150) | YES | | NULL | |
| shell | char(50) | YES | | NULL | |
+----------+-----------+------+-----+---------+-------+
7 rows in set (0.01 sec)

mysql> load data infile "/mydata/passwd" into table user1 fields terminated by ":" lines terminated by "\n";
Query OK, 41 rows affected (0.00 sec)
Records: 41 Deleted: 0 Skipped: 0 Warnings: 0

mysql> alter table user1 add id int(2) primary key auto_increment first;
Query OK, 41 rows affected (0.33 sec)
Records: 41 Duplicates: 0 Warnings: 0

insert 插入的四种方式
注意事项
-字段值要与字段类型相匹配
-对应字符类型的字段，要用双或单引号括起来
-依次给所有字段赋值，字段名可以省
只给一部分字段赋值时，必须明确写出对应的字段名称
mysql> insert into user1 values(42,"bob","x",3000,3000,"student user","/home/bob","/bin/bash");
Query OK, 1 row affected (0.00 sec)

mysql> insert into user1 values(43,"bob","x",3000,3000,"student user","/home/bob","/bin/bash"),(44,"bbb","x",3000,3000,"student user","/home/bob","/bin/bash");
Query OK, 2 rows affected (0.00 sec)
Records: 2 Duplicates: 0 Warnings: 0

mysql> insert into user1(name,uid ,gid) values ("lili",29,30);
Query OK, 1 row affected (0.00 sec)

mysql> insert into user1(name,uid ,gid) values ("lili",29,30),("yy",29,32);
Query OK, 2 rows affected (0.00 sec)
Records: 2 Duplicates: 0 Warnings: 0

select查询的两种方式
mysql> select * from user1;
mysql> select * from user1 where id =32;

update
修改全部
mysql> update user1 set password ="A";
Query OK, 47 rows affected (0.00 sec)
Rows matched: 47 Changed: 47 Warnings: 0
按条件修改
mysql> update user1 set password ="A" where name="root";
Query OK, 0 rows affected (0.00 sec)
Rows matched: 1 Changed: 0 Warnings: 0

delect

mysql> delete from user1 where id=43;
Query OK, 1 row affected (0.00 sec)

mysql> delete from user1

匹配条件
基本匹配条件：适用于select update delete
数值比较 > < != >= <= =
select * from user1 where id =10;
update user1 set password="B" where id<=10;
delete from user1 where uid >=3000;
字符比较 = !=
select * from user1 where name="root";
select name,shell from user1 where name!="root";

匹配空 is null
匹配非空 is not null
select name,uid from user1 where id is null;
update user1 set uid=250 where uid is null;
delete from user1 where uid is null;

逻辑比较
and
逻辑与 and
或 or
非！ not 取反

范围内匹配
in(值列表) 在...里...
delete from user1 where name in ("zhangsan","mysql","rsync","apache");
not in(值列表) 不在..里..

Between 数字1 and 数字2 在..之间
select * from user1 where id between 10 and 25;
DISTINCT 字段名去重显示
select distinct shell from user1 where uid>=100;
高级匹配条件：适用于select update delete
模糊匹配like
-一个字符
% 0个或者多个
insert into user1(id,name)values(67,null),(69,""); ---null是代表什么都没有，不是0

select name from user1 where name like '_';
select name from user1 where name like '_%_';
select name from user1 where name like 'a_';
select name from user1 where name like '%';

正则匹配 regrexp '正则表达式'
^开头
$结尾
[ ]
* 0个或者多个
.位数
select name from user1 where name regexp '^a'; 以a开头的
select name from user1 where name regexp 'a'; 包含a
select name from user1 where name regexp '[0-9]'; 名字里面有数据的
select name from user1 where name regexp '[0-9]$';
select name,uid from user1 where uid regexp '...';
select name,uid from user1 where uid regexp '^...$';
select name,uid from user1 where uid regexp 'r.*t';
select name,uid from user1 where name regexp '^r.*t$';

四则运算适用于 select update
+
-
*
/
%
select name,uid from user1 where uid >=10 and uid <=20;
update user1 set uid=uid+1 where uid >=10 and uid <=20;
alter table user1 add age int(2) default 19 after name;
select name,age from user1 where name="root";
select name,2018-age s_year from user1 where name="root";
select name,uid,gid,(uid+gid)/2 pjz from user1;

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