DBAmysql数据库2

[root@host50 ~]# mysql -hlocalhost -uroot -p'*-ZPqB——第一次登陆是要默认密码登陆

mysql> show databases; ————查看库，提示需要修改默认密码

ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.

mysql> alter user root@"localhost"identified by "123456"————修改默认密码，提示不符合密码规则，要么符合密码规则，或者修改密码规则。密码太负责不利于记忆不进行修改密码就不能进行创建库等操作 -> ;

ERROR 1819 (HY000): Your password does not satisfy the current policy requirements

mysql> set global validate_password_policy=0;——修改密码规则

Query OK, 0 rows affected (0.00 sec)

mysql> set global validate_password_length=6;——修改密码规则

Query OK, 0 rows affected (0.00 sec)

mysql> alter user root@"localhost" identified by "123456";——修改密码

Query OK, 0 rows affected (0.00 sec)

mysql> qiut

[root@host50 ~]# mysql -hlocalhost -uroot -p——再一次登陆

Enter password:

mysql> show databases;——展示库名单

+--------------------+

| Database |

+--------------------+

| information_schema |

| mysql |

| performance_schema |

| sys |

+--------------------+

4 rows in set (0.00 sec)

mysql>

mysql> create database gamedb; ——创建库

Query OK, 1 row affected (0.00 sec)

mysql> create database buydb;——创建库

Query OK, 1 row affected (0.00 sec)

mysql> create database bbsdb;——创建库

Query OK, 1 row affected (0.00 sec)

mysql> show databases;——展示库

+--------------------+

| Database |

+--------------------+

| information_schema |

| bbsdb |

| buydb |

| gamedb |

| mysql |

| performance_schema |

| sys |

+--------------------+

7 rows in set (0.00 sec)

命令行创建库和sql命令创建库的不同之处

mkdir /var/log/mysql/db1——命令行进行创建库

————不管那一种方法都是可以创建一个文件夹，但是创建的目录的所属者和所属组就不一样。一个是root一个是MySQL

这样建立时没有w权限

[root@host50 ~]# mkdir /var/lib/mysql/db2

mysql> show databases;

+--------------------+

| Database |

+--------------------+

| information_schema |

| buydb |

| db1 |

| db2 |

| gamedb |

| mysql |

| performance_schema |

| sys |

+--------------------+

[root@host50 ~]# ls -ld /var/lib/mysql/db1

drwxr-x---. 2 mysql mysql 20 7月 10 14:12 /var/lib/mysql/db1

[root@host50 ~]# ls -ld /var/lib/mysql/db2

drwxr-xr-x. 2 root root 6 7月 10 14:27 /var/lib/mysql/db2——其他用户没有w权限，在SQL没有写入的权限

修改方法1.给其他用户添加w权限。

SQL 命令 ————结构化查询语言（中文名称）

库的管理命令??? 查看删除撤换创建

数据库的命名规则

可以用数字字母下划线不能有纯数字；

区分大小写，，具有唯一性；

以；结束命令 \c终止命令

表的管理命令创建表查看表内容查看表结构删除表写入数据

表必须创在库里面表相当于系统文件

数据的存储取决于对象

创建表创建表结构

mysql> create database studb;——创建库

mysql> use studb;——进入库，表必须创建在库里面

mysql> create table studb.stuinfo( name char(15), sex char(10), age int, tel char(11) );————创建表

mysql> desc studb.stuinfo;——进入表

mysql> select * from studb.stuinfo;——查看表记录

+-------+----------+------+-----+---------+-------+

+-------+----------+------+-----+---------+-------+

| sex | char(10) | YES | | NULL | |

| age | int(11) | YES | | NULL | |

| tel | char(11) | YES | | NULL | |

+-------+----------+------+-----+---------+-------+

mysql> select * from studb.stuinfo;——还没有写入数据，显示为空

Empty set (0.00 sec)

mysql> insert into studb.stuinfo values("bob","boy",21,"88888") , ——数字可以不用双引 ("tangmingqi","boy",27,"13527898646");

Query OK, 2 rows affected (0.05 sec)————给表写入数据

Records: 2 Duplicates: 0 Warnings: 0

mysql> select * from studb.stuinfo;————查看表里的记录

+------------+------+------+-------------+

| name | sex | age | tel |

+------------+------+------+-------------+

| bob | boy | 21 | 88888 |

| tangmingqi | boy | 27 | 13527898646 |

+------------+------+------+-------------+

2 rows in set (0.00 sec)

mysql> update studb.stuinfo set sex="girl";——更改表里的数据

Query OK, 2 rows affected (0.04 sec)

Rows matched: 2 Changed: 2 Warnings: 0

mysql> select * from studb.stuinfo; ——查看表里的数据

+------------+------+------+-------------+

| name | sex | age | tel |

+------------+------+------+-------------+

| bob | girl | 21 | 88888 |

| tangmingqi | girl | 27 | 13527898646 |

+------------+------+------+-------------+

2 rows in set (0.00 sec)

mysql> select database(); ———查看当前的信息

+------------+

| database() |

+------------+

| studb |

+------------+

1 row in set (0.00 sec)

mysql> delete from studb.stuinfo; ——删除表里的数据

Query OK, 2 rows affected (0.02 sec)

mysql> select * from studb.stuinfo; ————查看表里数据

Empty set (0.00 sec)

mysql> show tables; ————查看表

+-----------------+

| Tables_in_studb |

+-----------------+

| stuinfo |

+-----------------+

1 row in set (0.00 sec)

mysql> drop table stuinfo; ————删除表

Query OK, 0 rows affected (0.08 sec)

mysql> show tables; ————查看表

Empty set (0.00 sec)

字符集？？

mysql> use studb; ——进入库

mysql> create table 学生表(姓名 char(10),年龄 int)default charset=utf8; —创建中文的数据表

Query OK, 0 rows affected (0.20 sec)

mysql> show create table 学生表; ————展示表结构

| 学生表 | CREATE TABLE `学生表` (

`姓名` char(10) DEFAULT NULL,

`年龄` int(11) DEFAULT NULL

) ENGINE=InnoDB DEFAULT CHARSET=utf8 |

+-----------+---------------------------------

insert into 学生表 values("张三丰",108); ————中文插入数据

Query OK, 1 row affected (0.02 sec)

mysql> select * from 学生表; ————展示表数据

+-----------+--------+

| 姓名 | 年龄 |

+-----------+--------+

| 张三丰 | 108 |

+-----------+--------+

1 row in set (0.00 sec)

Mysql 数据类型：

建表的时候设计一个合理的数据类型 ———表结构

整数型——又可以分好几类

用得最多的是INT

小数型（浮点型）

DOUBLE 双精度浮点数 8个字节

常见的信息种类

mysql> use db1

Database changed

mysql> select database();

+------------+

| database() |

+------------+

| db1 |

+------------+

1 row in set (0.00 sec)

mysql> create table t1(level tinyint); 数值 -128 ～127 之间的数值建有符合的数据存储表

Query OK, 0 rows affected (0.25 sec)

mysql> desc t1;

+-------+------------+------+-----+---------+-------+

+-------+------------+------+-----+---------+-------+

+-------+------------+------+-----+---------+-------+

1 row in set (0.00 sec)

mysql> select * from t1;————表里是否有记录

Empty set (0.00 sec)

mysql> create table t2(level tinyint unsigned);

mysql> desc t2

-> ;

+-------+---------------------+------+-----+---------+-------+

+-------+---------------------+------+-----+---------+-------+

+-------+---------------------+------+-----+---------+-------+

1 row in set (0.00 sec)

mysql> select * from t2;

Empty set (0.00 sec)

mysql> insert into t2 values(-1); ————超出存储范围

ERROR 1264 (22003): Out of range value for column 'level' at row 1

mysql> insert into t2 values(0); ————存储范围0～255

Query OK, 1 row affected (0.03 sec)

mysql> insert into t2 values(255); ————存储范围0～255

Query OK, 1 row affected (0.03 sec)

mysql> insert into t2 values(256); ————超出存储范围

ERROR 1264 (22003): Out of range value for column 'level' at row 1

mysql> select * from t2; ————表的存储数据

+-------+

| level |

+-------+

| 0 |

| 255 |

+-------+

2 rows in set (0.00 sec)

mysql> insert into t2 values(1.256);

Query OK, 1 row affected (0.04 sec)

mysql> select * from t2;

+-------+

| level |

+-------+

| 0 |

| 255 |

| 1 |

+-------+

3 rows in set (0.00 sec)

mysql> create table t3(pay float(5,2));

Query OK, 0 rows affected (0.27 sec)

mysql> desc t3;

+-------+------------+------+-----+---------+-------+

+-------+------------+------+-----+---------+-------+

| pay | float(5,2) | YES | | NULL | |

+-------+------------+------+-----+---------+-------+

1 row in set (0.01 sec)

建立一个浮点型的数据表

mysql> insert into t3 values(1118.26);

ERROR 1264 (22003): Out of range value for column 'pay' at row 1

mysql> insert into t3 values(118.26);

Query OK, 1 row affected (0.03 sec)

mysql> insert into t3 values(280);

Query OK, 1 row affected (0.03 sec)

mysql> insert into t3 values(0.26002225555);

Query OK, 1 row affected (0.03 sec)

mysql> insert into t3 values(1111.26002225555);

ERROR 1264 (22003): Out of range value for column 'pay' at row 1

一共是位数，小数位只有两位，不管数多少位小数，都精确到两位。。但是整体不能超过五个数

mysql> select * from t3;

+--------+

| pay |

+--------+

| 118.26 |

| 280.00 |

+--------+

2 rows in set (0.00 sec)

字符类型

char ————定长255个字符存储不够指定的长度时，就会在右边自动补齐超出宽带就不能存储成功，生产环境用得比较多

varchar ————变长 66532个字符，有大量数据写入的时候，CPU 就会暂用，没有时间处理其他访问

text

blob

mysql 数据库能存那些文件？？ char varchar text blob ——用空间换时间

数值字符音频文件图片视频文件

/root/media/film/xxx.avi

mysql> create table t7 (gamemame char(15),level smallint,pay float(7.2));

Query OK, 0 rows affected (0.21 sec)

mysql> select * from t7;

Empty set (0.00 sec)

mysql> desc t7;

+----------+-------------+------+-----+---------+-------+

+----------+-------------+------+-----+---------+-------+

| pay | float | YES | | NULL | |

+----------+-------------+------+-----+---------+-------+

3 rows in set (0.00 sec)

mysql> insert into t7 values("zbj",250,1880.22);

Query OK, 1 row affected (0.02 sec)

mysql> select * from t7;

+----------+-------+---------+

| gamemame | level | pay |

+----------+-------+---------+

| zbj | 250 | 1880.22 |

+----------+-------+---------+

1 row in set (0.00 sec)

枚举类型：让字段的值，在规定的范围内选择

enum （值列表）单选

set (值列表) 多选

mysql> create table t8 (name char(15),sex enum("boy","girl","no"),likes set ("game","film","eat","sleep"));

Query OK, 0 rows affected (0.25 sec)

mysql> desc t8;

+-------+----------------------------------+------+-----+---------+-------+

+-------+----------------------------------+------+-----+---------+-------+

| sex | enum('boy','girl','no') | YES | | NULL | |

+-------+----------------------------------+------+-----+---------+-------+

3 rows in set (0.00 sec)

mysql> insert into t8 values("bob","man","it,book");

ERROR 1265 (01000): Data truncated for column 'sex' at row 1

mysql> insert into t8 values("bob","boy","eat,sleep");

Query OK, 1 row affected (0.03 sec)

mysql> select * from t8;

+------+------+-----------+

| name | sex | likes |

+------+------+-----------+

| bob | boy | eat,sleep |

+------+------+-----------+

1 row in set (0.00 sec)

日期时间类型

年 year yyyy 2018

日期 date yyyymmdd 20181138 都有自己的存储空间1901～2055年

时间 time HHMMSS 083000

日期时间 datetime YYYYMMDDHHMMSS

timestamp 20180807123723

mysql> create table t2(name char(15), brithday date, work time, s_year year, meetting datetime);

——为一个表赋值

Query OK, 0 rows affected (0.19 sec)

mysql> desc t2;

+----------+----------+------+-----+---------+-------+

+----------+----------+------+-----+---------+-------+

+----------+----------+------+-----+---------+-------+

5 rows in set (0.00 sec)

mysql> insert into t2 values("liuhai",19891223,180000,2013,20181009203000);——值入数据

Query OK, 1 row affected (0.02 sec)

mysql> select * from t2; ——查看表记录

+--------+------------+----------+--------+---------------------+

+--------+------------+----------+--------+---------------------+

| liuhai | 1989-12-23 | 18:00:00 | 2013 | 2018-10-09 20:30:00 |

+--------+------------+----------+--------+---------------------+

1 row in set (0.00 sec)

mysql> insert into t2 values("zuhai",19761232,180000,2013,20181009203000);——语法格式错误

ERROR 1292 (22007): Incorrect date value: '19761232' for column 'brithday' at row 1

mysql> insert into t2 values("liuhai2",19881223,070000,95,20131009210000),("zuhai1",19781223,200000,23,20180807123000);——可以以，分割继续插入信息

Query OK, 2 rows affected (0.02 sec)

Records: 2 Duplicates: 0 Warnings: 0

mysql> select * from t2;——查看表信息

+---------+------------+----------+--------+---------------------+

+---------+------------+----------+--------+---------------------+

| liuhai | 1989-12-23 | 18:00:00 | 2013 | 2018-10-09 20:30:00 |

| zuhai | 1976-12-12 | 18:00:00 | 2013 | 2018-10-09 20:30:00 |

| liuhai2 | 1988-12-23 | 07:00:00 | 1995 | 2013-10-09 21:00:00 |

| zuhai1 | 1978-12-23 | 20:00:00 | 2023 | 2018-08-07 12:30:00 |

+---------+------------+----------+--------+---------------------+

4 rows in set (0.00 sec)

Datetime 和 timestamp 的区别

占据的空间和赋值的范围不一样

mysql> create table t3(meetting datetime, party timestamp);

Query OK, 0 rows affected (0.16 sec)

mysql> desc t3;

+----------+-----------+------+-----+-------------------+-----------------------------+

+----------+-----------+------+-----+-------------------+-----------------------------+

+----------+-----------+------+-----+-------------------+-----------------------------+

2 rows in set (0.00 sec)

mysql> insert into t3 values(20170711122356,20180807122345);

Query OK, 1 row affected (0.06 sec)

mysql> select * from t3;

+---------------------+---------------------+

| meetting | party |

+---------------------+---------------------+

| 2017-07-11 12:23:56 | 2018-08-07 12:23:45 |

+---------------------+---------------------+

1 row in set (0.00 sec)

mysql> insert into t3(party) values (20160711103625);

Query OK, 1 row affected (0.03 sec)

mysql> select * from t3;

+---------------------+---------------------+

| meetting | party |

+---------------------+---------------------+

| 2017-07-11 12:23:56 | 2018-08-07 12:23:45 |

| NULL | 2016-07-11 10:36:25 |

+---------------------+---------------------+

2 rows in set (0.00 sec)

mysql> insert into t3(meetting) values (20180912101512);

Query OK, 1 row affected (0.04 sec)

mysql> select * from t3;

+---------------------+---------------------+

| meetting | party |

+---------------------+---------------------+

| 2017-07-11 12:23:56 | 2018-08-07 12:23:45 |

| NULL | 2016-07-11 10:36:25 |

| 2018-09-12 10:15:12 | 2018-07-11 10:38:15 |

+---------------------+---------------------+

3 rows in set (0.00 sec)

[root@host50 ~]# date

2018年 07月 11日星期三 10:39:24 CST

用函数给时间赋值 ——MYSQL服务的内置的命令年月日的操作方法都是一样

mysql> select now();

+---------------------+

| now() |

+---------------------+

| 2018-07-11 10:43:16 |

+---------------------+

1 row in set (0.00 sec)

mysql> select year(now());

+-------------+

| year(now()) |

+-------------+

| 2018 |

+-------------+

1 row in set (0.01 sec

mysql> select month(20180410);

+-----------------+

| month(20180410) |

+-----------------+

| 4 |

+-----------------+

1 row in set (0.00 sec)

mysql> select date( now() ); ——当前系统的年月日

+-----------------+

| date( now() ) |

+-----------------+

| 2018-07-11 |

+-----------------+

1 row in set (0.00 sec)

mysql> select day( now() );

+---------------+

| day( now() ) |

+---------------+

| 11 |

+---------------+

1 row in set (0.00 sec)

mysql> select time( now() );

+-----------------+

| time( now() ) |

+-----------------+

| 10:48:43 |

+-----------------+

1 row in set (0.00 sec)

mysql> select month( now() );

+----------------+

| month( now() ) |

+----------------+

| 7 |

+----------------+

1 row in set (0.00 sec)

mysql> select year( now() );

+---------------+

| year( now() ) |

+---------------+

| 2018 |

+---------------+

1 row in set (0.00 sec)

mysql> insert into t2 values("lihhai1",date(1223),090000,year(19881225),now());

Query OK, 1 row affected (0.02 sec)

mysql> select * from t2;

+---------+------------+----------+--------+---------------------+

+---------+------------+----------+--------+---------------------+

| liuhai | 1989-12-23 | 18:00:00 | 2013 | 2018-10-09 20:30:00 |

| zuhai | 1976-12-12 | 18:00:00 | 2013 | 2018-10-09 20:30:00 |

| liuhai2 | 1988-12-23 | 07:00:00 | 1995 | 2013-10-09 21:00:00 |

| zuhai1 | 1978-12-23 | 20:00:00 | 2023 | 2018-08-07 12:30:00 |

| lihhai1 | 2000-12-23 | 09:00:00 | 1988 | 2018-07-11 11:04:19 |

+---------+------------+----------+--------+---------------------+

5 rows in set (0.00 sec)

unsigned ——无符号

mysql> create table t4(id int(4) unsigned zerofill,age int(2) unsigned zerofill);

Query OK, 0 rows affected (0.14 sec)

mysql> desc t4;

+-------+--------------------------+------+-----+---------+-------+

+-------+--------------------------+------+-----+---------+-------+

| id | int(4) unsigned zerofill | YES | | NULL | |

| age | int(2) unsigned zerofill | YES | | NULL | |

+-------+--------------------------+------+-----+---------+-------+

2 rows in set (0.00 sec)

mysql> insert into t4 values (5,7);

Query OK, 1 row affected (0.03 sec)

mysql> select t4;

ERROR 1054 (42S22): Unknown column 't4' in 'field list'

mysql> select * from t4;

+------+------+

| id | age |

+------+------+

| 0005 | 07 |

+------+------+

1 row in set (0.00 sec)

mysql> insert into t4 values (1199,211);

Query OK, 1 row affected (0.04 sec)

mysql> select * from t4;

+------+------+

| id | age |

+------+------+

| 0005 | 07 |

| 1199 | 211 |

+------+------+

2 rows in set (0.00 sec)

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