一、字符集
1.列出可用字符集
show character set;
2.列出一個字符集的校對規則
show collation like 'latin1%'
3.數據庫字符集和校對規則
create database li default character set latin1 collate latin1_swedish_ci;
4.服務器字符集和校對規則
（1）編譯時指定參數設置
./configure --with-charset=latin1 --with-collation=latin1_german1_ci
（2）啓動mysql時初始選項設置
mysqld --default-character-set=latin1 --default-collation=latin1_swedish_ci
5.表字符集和校對規則
create table test1 (id int,name char(20)) default character set latin1 collate latin1_danish_ci;
6.列字符集和校對規則
create table test2 (coll1 varchar(5) character set latin1 collate latin1_german1_ci);
7顯示全部可用的字符集
show character set like 'latin1%';
8.顯示創建數據庫語句
show create database li;
9.顯示用戶的連接數
show processlist（默認列出100條）
show full processlist（列出全部的）
二、sql語句詳解
1.alter語句
（1）更改列名
alter table test change id number integer; 將一個int類型列的id重命名爲number
（2）更改列類型
alter table test change number a bigint;
2.drop語句
（1）drop數據庫
drop database li;
（2）drop索引
drop index test3;
（3）drop表
drop table test;
3.rename語句
（1）rename 表
rename table test1 to test;
4.delete語句
delete from test;
5.insert語句
insert into test (id,name) values (1,'lisi')
6.load data file語句
LOAD DATA INFILE 'data.txt' INTO TABLE db2.my_table;
三、用戶管理
1.創建用戶
create user wang@localhost identified by '123456';
2.刪除用戶
drop user wang@localhost;
3.創建授權用戶
grant create,delete on test.* to wang@'192.168.10.%' identified by '123456'
4.查看用戶
select user,host from mysql.user;
5.刷新授權表
flush privileges;
6.查看用戶權限
show grants for wang;
7.更改密碼
如果是初始登陸的話，是空密碼，需要設置
mysqladmin -uroot -password '123456'
如果已知原密碼再改密碼
mysqladmin -uroot -p123456 password '1234567'
如果是已經改了但是又忘了，並且已經退出了Mysql的登錄，則需要跳過授權表啓動mysql
首先停掉正在運行的mysql
然後mysqld_safe --skip-grant-tables &
mysql -uroot
update mysql.user set password=password('123456') where user='root';
flush privileges;
查看用戶
select user();
四、mysql監控
1.查看某個數據庫的磁盤使用空間
select concat(truncate(sum(data_length)/1024/1024,2),'MB') as data_size,
concat(truncate(sum(max_data_length)/1024/1024,2),'MB') as max_data_size,
concat(truncate(sum(data_free)/1024/1024,2),'MB') as data_free,
concat(truncate(sum(index_length)/1024/1024,2),'MB') as index_size
from information_schema.tables where TABLE_SCHEMA = 'databasename';
2.查看所有的數據庫的磁盤空間
select TABLE_SCHEMA,concat(truncate(sum(data_length)/1024/1024,2),'MB') as data_size, concat(truncate(sum(max_data_length)/1024/1024,2),'MB') as max_data_size,
concat(truncate(sum(data_free)/1024/1024,2),'MB') as data_free,
concat(truncate(sum(index_length)/1024/1024,2),'MB') as index_size
from information_schema.tables group by TABLE_SCHEMA;
3.查詢某張表的空間
select concat(truncate(sum(data_length)/1024/1024,2),'MB') as data_size,
concat(truncate(sum(max_data_length)/1024/1024,2),'MB') as max_data_size,
concat(truncate(sum(data_free)/1024/1024,2),'MB') as data_free,
concat(truncate(sum(index_length)/1024/1024,2),'MB') as index_size
from information_schema.tables
where TABLE_NAME = 'tablename';