[gaowanlu@vhost02 a5game_data]$ which mysql
/usr/bin/mysql
[gaowanlu@vhost02 a5game_data]$ which mysqld
/usr/sbin/mysqld
[gaowanlu@vhost02 a5game_data]$ 

./bin/mysqld

/usr/sbin/mysqld

mysqld

[gaowanlu@vhost02 bin]$ ps -ef | grep mysqld
mysql      1595      1  0 Feb27 ?        00:00:00 /bin/sh /usr/bin/mysqld_safe --basedir=/usr
mysql      1760   1595  0 Feb27 ?        00:03:11 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib64/mysql/plugin --log-error=/var/log/mysqld.log --pid-file=/var/run/mysqld/mysqld.pid --socket=/var/lib/mysql/mysql.sock
gaowanlu  37846  17788  0 15:12 pts/5    00:00:00 grep --color=auto mysqld

mysql.server start
mysql.server stop

"完整的可执行文件路径" --install [-manual] [服务名]

"C:\Program Files\MySQL\MySQL Server 5.7\bin\mysqld" --install
net start MySQL
net stop MySQL

mysql -h主机名 -u用户 -p密码 -P端口

mysql> quit
mysql> exit
mysql> \q

mysqld -P3307

#服务器
mysqld --socket=/tmp/a.txt
#客户端
mysqld -hlocalhost -u root --socket=/tmp/a.txt -p

mysql> SHOW ENGINES;
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| Engine             | Support | Comment                                                        | Transactions | XA   | Savepoints |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| FEDERATED          | NO      | Federated MySQL storage engine                                 | NULL         | NULL | NULL       |
| MRG_MYISAM         | YES     | Collection of identical MyISAM tables                          | NO           | NO   | NO         |
| MyISAM             | YES     | MyISAM storage engine                                          | NO           | NO   | NO         |
| BLACKHOLE          | YES     | /dev/null storage engine (anything you write to it disappears) | NO           | NO   | NO         |
| CSV                | YES     | CSV storage engine                                             | NO           | NO   | NO         |
| MEMORY             | YES     | Hash based, stored in memory, useful for temporary tables      | NO           | NO   | NO         |
| ARCHIVE            | YES     | Archive storage engine                                         | NO           | NO   | NO         |
| InnoDB             | DEFAULT | Supports transactions, row-level locking, and foreign keys     | YES          | YES  | YES        |
| PERFORMANCE_SCHEMA | YES     | Performance Schema                                             | NO           | NO   | NO         |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
9 rows in set (0.01 sec)

CREATE TABLE 表名(
    建表语句；
) ENGINE = 存储引擎名称;

ALTER TABLE 表名 ENGINE = 存储引擎名称;

mysqld --skip-networking

mysqld --default-storage-engine-MyISAM

mysqld --help
mysqld_safe --help

--host -h  主机名
--user -u 用户名
--password -p 密码
--port -P 端口
--version -V 版本信息

/etc/my.cnf
/etc/mysql/my.cnf
SYSCONFDIR/my.cnf
$MYSQL_HOME/my.cnf 特定于服务器选项
default-extra-file 命令行指定的额外配置文件路径
~/.my.cnf 特定于用户的选项
~/.mylogin.cnf 特定于用户的登录路径选项

[server]
[具体的启动选项...]

[mysqld]
[具体的启动选项...]

[mysqld_safe]
[具体的启动选项...]

[client]
[具体的启动选项...]

[mysql]
[具体的启动选项...]

[mysqladmin]
[具体的启动选项...]

mysqld [mysqld] [server]
mysqld_safe [mysqld] [server] [mysqld_safe]
mysql_server [mysqld] [server] [mysql.server]
mysql [mysql] [client]
mysqladmin [mysqladmin] [client]
mysqldump [mysqldump] [client]

SHOW VARIABLES; 
mysql> SHOW VARIABLES LIKE 'default_storage_engine';
+------------------------+--------+
| Variable_name          | Value  |
+------------------------+--------+
| default_storage_engine | InnoDB |
+------------------------+--------+
1 row in set, 1 warning (0.00 sec)
mysql> SHOW VARIABLES LIKE 'max_connections';
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| max_connections | 151   |
+-----------------+-------+
1 row in set, 1 warning (0.00 sec)

mysql> SHOW VARIABLES LIKE 'default%';
+-------------------------------+-----------------------+
| Variable_name                 | Value                 |
+-------------------------------+-----------------------+
| default_authentication_plugin | caching_sha2_password |
| default_collation_for_utf8mb4 | utf8mb4_0900_ai_ci    |
| default_password_lifetime     | 0                     |
| default_storage_engine        | InnoDB                |
| default_table_encryption      | OFF                   |
| default_tmp_storage_engine    | InnoDB                |
| default_week_format           | 0                     |
+-------------------------------+-----------------------+
7 rows in set, 1 warning (0.00 sec)

SET [GLOBAL|SESSION] 系统变量名 = 值
# 默认为SESSION范围的

SHOW [GLOBAL|SESSION] VARIABLES [LIKE 匹配的模式]

SHOW [GLOBAL|SESSION] STATUS [LIKE 匹配的模式]

mysql> SHOW STATUS LIKE 'thread%' ;
+-------------------+-------+
| Variable_name     | Value |
+-------------------+-------+
| Threads_cached    | 0     |
| Threads_connected | 4     |
| Threads_created   | 4     |
| Threads_running   | 2     |
+-------------------+-------+
4 rows in set (0.00 sec)

'L' -> 01001100 (十六进制 0x4c 十进制76)
'M' -> 01001101 (十六进制 0x4D 十进制77)

'L' -> 01001100 (1宇节，十六进制0x4C)
'啊'-> 111001011001010110001010 （3宇节，十六进制0xE5958A）

UTF-8 3字节，十六进制形式为 0xE68891
GB2312 2字节，十六进制形式为 0xCED2

SHOW (CHARACTER SET|CHARSET) [LIKE 匹配的模式]

mysql> SHOW CHARSET;
+----------+---------------------------------+---------------------+--------+
| Charset  | Description                     | Default collation   | Maxlen |
+----------+---------------------------------+---------------------+--------+
| armscii8 | ARMSCII-8 Armenian              | armscii8_general_ci |      1 |
| ascii    | US ASCII                        | ascii_general_ci    |      1 |
| big5     | Big5 Traditional Chinese        | big5_chinese_ci     |      2 |
| binary   | Binary pseudo charset           | binary              |      1 |
| cp1250   | Windows Central European        | cp1250_general_ci   |      1 |
| cp1251   | Windows Cyrillic                | cp1251_general_ci   |      1 |
| cp1256   | Windows Arabic                  | cp1256_general_ci   |      1 |
| cp1257   | Windows Baltic                  | cp1257_general_ci   |      1 |
| cp850    | DOS West European               | cp850_general_ci    |      1 |
| cp852    | DOS Central European            | cp852_general_ci    |      1 |
| cp866    | DOS Russian                     | cp866_general_ci    |      1 |
| cp932    | SJIS for Windows Japanese       | cp932_japanese_ci   |      2 |
| dec8     | DEC West European               | dec8_swedish_ci     |      1 |
| eucjpms  | UJIS for Windows Japanese       | eucjpms_japanese_ci |      3 |
| euckr    | EUC-KR Korean                   | euckr_korean_ci     |      2 |
| gb18030  | China National Standard GB18030 | gb18030_chinese_ci  |      4 |
| gb2312   | GB2312 Simplified Chinese       | gb2312_chinese_ci   |      2 |
| gbk      | GBK Simplified Chinese          | gbk_chinese_ci      |      2 |
| geostd8  | GEOSTD8 Georgian                | geostd8_general_ci  |      1 |
| greek    | ISO 8859-7 Greek                | greek_general_ci    |      1 |
| hebrew   | ISO 8859-8 Hebrew               | hebrew_general_ci   |      1 |
| hp8      | HP West European                | hp8_english_ci      |      1 |
| keybcs2  | DOS Kamenicky Czech-Slovak      | keybcs2_general_ci  |      1 |
| koi8r    | KOI8-R Relcom Russian           | koi8r_general_ci    |      1 |
| koi8u    | KOI8-U Ukrainian                | koi8u_general_ci    |      1 |
| latin1   | cp1252 West European            | latin1_swedish_ci   |      1 |
| latin2   | ISO 8859-2 Central European     | latin2_general_ci   |      1 |
| latin5   | ISO 8859-9 Turkish              | latin5_turkish_ci   |      1 |
| latin7   | ISO 8859-13 Baltic              | latin7_general_ci   |      1 |
| macce    | Mac Central European            | macce_general_ci    |      1 |
| macroman | Mac West European               | macroman_general_ci |      1 |
| sjis     | Shift-JIS Japanese              | sjis_japanese_ci    |      2 |
| swe7     | 7bit Swedish                    | swe7_swedish_ci     |      1 |
| tis620   | TIS620 Thai                     | tis620_thai_ci      |      1 |
| ucs2     | UCS-2 Unicode                   | ucs2_general_ci     |      2 |
| ujis     | EUC-JP Japanese                 | ujis_japanese_ci    |      3 |
| utf16    | UTF-16 Unicode                  | utf16_general_ci    |      4 |
| utf16le  | UTF-16LE Unicode                | utf16le_general_ci  |      4 |
| utf32    | UTF-32 Unicode                  | utf32_general_ci    |      4 |
| utf8mb3  | UTF-8 Unicode                   | utf8mb3_general_ci  |      3 |
| utf8mb4  | UTF-8 Unicode                   | utf8mb4_0900_ai_ci  |      4 |
+----------+---------------------------------+---------------------+--------+
41 rows in set (0.08 sec)

SHOW COLLATION [LIKE 匹配的模式];

mysql> SHOW COLLATION LIKE 'utf8%';
+-----------------------------+---------+-----+---------+----------+---------+---------------+
| Collation                   | Charset | Id  | Default | Compiled | Sortlen | Pad_attribute |
+-----------------------------+---------+-----+---------+----------+---------+---------------+
| utf8mb3_bin                 | utf8mb3 |  83 |         | Yes      |       1 | PAD SPACE     |
| utf8mb3_croatian_ci         | utf8mb3 | 213 |         | Yes      |       8 | PAD SPACE     |
| utf8mb3_czech_ci            | utf8mb3 | 202 |         | Yes      |       8 | PAD SPACE     |
| utf8mb3_danish_ci           | utf8mb3 | 203 |         | Yes      |       8 | PAD SPACE     |
| utf8mb3_esperanto_ci        | utf8mb3 | 209 |         | Yes      |       8 | PAD SPACE     |
...
...
117 rows in set (0.00 sec)

后缀    英文意义    描述
_ai     accent insensitive 不区分重音
_as     accent sensitive    区分重音
_ci     case insensitive    不区分大小写
_cs     case    sensitive   区分大小写
_bin    binary      以二进制方式比较

系统变量    描述
character_set_server    服务器级别的字符集
collation_server    服务器级别的比较规则

mysql> SHOW VARIABLES LIKE 'character_set_server';
+----------------------+---------+
| Variable_name        | Value   |
+----------------------+---------+
| character_set_server | utf8mb4 |
+----------------------+---------+
1 row in set (0.15 sec)

mysql> SHOW VARIABLES LIKE 'collation_server';
+------------------+--------------------+
| Variable_name    | Value              |
+------------------+--------------------+
| collation_server | utf8mb4_0900_ai_ci |
+------------------+--------------------+
1 row in set (0.01 sec)

CREATE DATABASE 数据库名
    [[DEFAULT] CHARACTER SET 字符集名称]
    [[DEFAULT] COLLATE 比较规则名称];
ALTER DATABASE 数据库名
    [[DEFAULT] CHARACTER SET 字符集名称]
    [[DEFAULT] COLLATE 比较规则名称];

系统变量    描述
character_set_database  当前数据库的字符集
collation_database  当前数据库的比较规则

mysql> use db_log;
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> SHOW VARIABLES LIKE 'character_set_database';
+------------------------+---------+
| Variable_name          | Value   |
+------------------------+---------+
| character_set_database | utf8mb4 |
+------------------------+---------+
1 row in set (0.00 sec)

mysql> SHOW VARIABLES LIKE 'collation_database';
+--------------------+--------------------+
| Variable_name      | Value              |
+--------------------+--------------------+
| collation_database | utf8mb4_0900_ai_ci |
+--------------------+--------------------+
1 row in set (0.00 sec)

CREATE TABLE 表名(列的信息)
    [[DEFAULT] CHARACTER SET 字符集名称]
    [COLLATE 比较规则名称];
ALTER TABLE 表名
    [[DEFAULT] CHARACTER SET 字符集名称]
    [COLLATE 比较规则名称];

CREATE TABLE 表名(
    列名 字符串类型 [CHARACTER SET 字符集名称] [COLLATE 比较规则名称],
    其他列...
);
ALTER TABLE 表名 MODIFY 列名 字符串类型 [CHARACTER SET 字符集名称] [COLLATE 比较规则名称];

mysql> INSERT INTO t(col) VALUES('我我');

看第一个字节0xE6,它的值大于0x7F(127),说明待取字符是两字节编码，GBK编码表查找0xE688对应字符。
继续读0x91,值也大于0x7F试图读下一个字节，发现后面没有了，所以这是个半字符。

root@kTY-HK3-QL-86139:/home/root/note# echo $LC_ALL
root@kTY-HK3-QL-86139:/home/root/note# echo $LC_CTYPE
root@kTY-HK3-QL-86139:/home/root/note# echo $LANG
C.UTF-8

SET character_set_client=latin1;

mysql> SET character_set_client=ascii;
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT '我';
+-----+
| ??? |
+-----+
| ??? |
+-----+
1 row in set, 1 warning (0.00 sec)

mysql> SHOW WARNINGS\G
*************************** 1. row ***************************
  Level: Warning
   Code: 1300
Message: Cannot convert string '\xE6\x88\x91' from ascii to utf8mb4
1 row in set (0.00 sec)

CREATE TABLE tt(
    c VARCHAR(100)
) ENGINE=INNODB CHARSET=utf8;

mysql> SELECT * FROM tt;
+--+
|c |
+--+
|我|
+--+

SELECT * FROM tt WHERE c = '我';

系统变量    描述
character_set_client 服务器认为请求是按照该系统变量指定的字符集进行编码的
character_set_connection 服务器在处理请求时，会把请求字节序列从character_set_client转换为character_set_connection
character_set_results 服务器采用该系统变量指定的字符集对返回给客户端的字符串进行编码

SET NAMES charset_name; 
上面这条语句与下面这3条语句的效果一样:
set character_set_client = charset_name;
set character_set_connection = charset_name;
set character_set_results = charset_name;

mysql --default-character-set=utf8mb4 -u username -p

<?php
$mysqli = new mysqli("localhost", "username", "password", "database");
$mysqli->set_charset("utf8mb4");

SELECT * FROM t ORDER BY col;

CREATE TABLE 表名(列的信息) ROW_FORMAT=行格式名称;
ALTER TABLE 表名 ROW_FORMAT=行格式名称。

CREATE TABLE users (
    id INT PRIMARY KEY AUTO_INCREMENT,
    name VARCHAR(100),
    email VARCHAR(100)
) ENGINE=InnoDB ROW_FORMAT=DYNAMIC;
ALTER TABLE users ROW_FORMAT=COMPRESSED;

例如有个表
c1 VARCHAR(10) | c2 VARCHAR(10) | c3 VARCHAR(10)
'aaaa'|'bbb'|'d'

实际占用字节数
0x04 0x03 0x01

01 03 04

## 溢出列

## DYNAMIC行格式和COMPRESSED行格式

# 盛放记录的大盒子InnoDB数据页结构

# 快速查询的秘籍B+树索引

# B+树索引的使用

# MySQL的数据目录

# InnoDB的表空间

# 单表访问方法

# 连接原理

# 基于成本的优化

# InnoDB统计数据是如何收集的

# 基于规则的优化内含子查询优化二三事

# 查询优化的百科全书EXPLAIN详解

# optimizer trace的神奇功效

# InnoDB的Buffer Pool

# 事务简介

# redo日志

# undo日志

# 事务隔离级别和MVCC

# 锁

# MySQL相关工具使用

如mysqldump等