mysql-学习笔记01-Tutorial

基于5.6

Chapter 3 -Tutorial 

修改提示符：

PROMPT \u@\h \d >

\D	完整的日期
\d	当前数据库
\h	服务器名称
\u	当前用户

3.一、链接或者断开SERVER

root 登陆建立用户，赋予权限，链接方式两种都可, 链接本地能够不➕-h

$ mysql -uroot -proot

 mysql>CREATE USER 'myuser'@'localhost' IDENTIFIED BY 'myuser';

 mysql>GRANT ALL ON test.* TO 'myuser'@'localhost'

$ mysql -umyuser -pmyuser

$ mysql -u myuser -p 

$ mysql -h localhost  -u myuser -p

 若是出现如下错误表示，MySQL server daemon (Unix) or service (Windows) 没有在运行

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock'

退出链接

mysql> quit
mysql> \q

快捷键： Control+D.

3.2 Entering Queries 输入查询

这部分并不须要选择任何数据库。查询当前时间，版本，用户，当计算器使用

mysql> SELECT VERSION(), CURRENT_DATE;
+------------+--------------+
| VERSION()  | CURRENT_DATE |
+------------+--------------+
| 5.6.40-log | 2018-07-19   |
+------------+--------------+
1 row in set (0.00 sec)

mysql>  SELECT VERSION(), CURRENT_DATE;
+------------+--------------+
| VERSION()  | CURRENT_DATE |
+------------+--------------+
| 5.6.40-log | 2018-07-19   |
+------------+--------------+
1 row in set (0.00 sec)

mysql> SELECT SIN(PI()/4), (4+1)*5;
+--------------------+---------+
| SIN(PI()/4)        | (4+1)*5 |
+--------------------+---------+
| 0.7071067811865475 |      25 |
+--------------------+---------+
1 row in set (0.00 sec)

mysql> SELECT VERSION(); SELECT NOW();
+------------+
| VERSION()  |
+------------+
| 5.6.40-log |
+------------+
1 row in set (0.00 sec)

+---------------------+
| NOW()               |
+---------------------+
| 2018-07-19 15:41:16 |
+---------------------+
1 row in set (0.00 sec)

musql> SELECT  USER(),CURRENT_DATE;
+------------------+--------------+
| USER()           | CURRENT_DATE |
+------------------+--------------+
| myuser@localhost | 2018-07-19   |
+------------------+--------------+
1 row in set (0.00 sec)

\c   切换回 mysql>

mysql> select 
    -> user()
    -> \c
mysql> 

其余提示符：

Prompt	Meaning
mysql>	Ready for new query
->	Waiting for next line of multiple-line query 多行SQL
'>	Waiting for next line, waiting for completion of a string that began with a single quote (')
">	Waiting for next line, waiting for completion of a string that began with a double quote (")
`>	Waiting for next line, waiting for completion of an identifier that began with a backtick (`)
/*>	Waiting for next line, waiting for completion of a comment that began with /*

 

3.3 Creating and Using a Database 建立和使用SQL语句

只显示有权限的数据库（privilege） USE, like  QUIT, 不须要分号做为结尾.只能写在一行

使用root添加权限：GRANT ALL ON test.* TO 'myuser'@'localhost' 

myuser@localhost (none) >SHOW DATABASES;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| test               |
+--------------------+
2 rows in set (0.00 sec)

myuser@localhost (none) > USE test
Database changed
myuser@localhost test >

3.3.1 Creating and Selecting a Database建立和查询数据库

 root 建立数据库，并赋予权限

root@localhost (none) >CREATE DATABASE menagerie;
Query OK, 1 row affected (0.00 sec)

root@localhost (none) >GRANT ALL ON menagerie.* TO 'myuser'@'localhost' 
    -> ;
Query OK, 0 rows affected (0.00 sec)

myuser 登陆并使用

myuser@localhost (none) >show databases
    -> ;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| menagerie          |
| test               |
+--------------------+
3 rows in set (0.00 sec)

myuser@localhost (none) >use menagerie
Database changed

 

3.3.2 Creating a Table

显示表

myuser@localhost (none) >show databases
    -> ;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| menagerie          |
| test               |
+--------------------+
3 rows in set (0.00 sec)

创建表

myuser@localhost menagerie > CREATE TABLE pet (name VARCHAR(20), owner VARCHAR(20),
    ->  species VARCHAR(20), sex CHAR(1), birth DATE, death DATE);
ERROR 2006 (HY000): MySQL server has gone away
No connection. Trying to reconnect...
Connection id:    57
Current database: menagerie

Query OK, 0 rows affected (0.07 sec)

 

varchar 字符串类型适合相似：name, owner, 和 species 这些列，由于他们的长度是变化的。

varchar 长度在1 到65535 之间。 可使用alter table 进行修改。

不少类型的值只有固定的选项，例如性别sex：'male' and'female'能够简化为'm' and 'f'

固定长处使用char类型。

用data 存储时间格式

显示表结构

myuser@localhost menagerie >SHOW TABLES;
ERROR 2006 (HY000): MySQL server has gone away
No connection. Trying to reconnect...
Connection id:    58
Current database: menagerie

+---------------------+
| Tables_in_menagerie |
+---------------------+
| pet                 |
+---------------------+
1 row in set (0.01 sec)

myuser@localhost menagerie >DESCRIBE pet;
+---------+-------------+------+-----+---------+-------+
| Field   | Type        | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+-------+
| name    | varchar(20) | YES  |     | NULL    |       |
| owner   | varchar(20) | YES  |     | NULL    |       |
| species | varchar(20) | YES  |     | NULL    |       |
| sex     | char(1)     | YES  |     | NULL    |       |
| birth   | date        | YES  |     | NULL    |       |
| death   | date        | YES  |     | NULL    |       |
+---------+-------------+------+-----+---------+-------+
6 rows in set (0.01 sec)

myuser@localhost menagerie >

 

3.3.3 Loading Data into a Table

建立你的表以后，你必须填充它，但是哟使用load data和insert 语句。默认的日期格式 'YYYY-MM-DD'

After creating your table, you need to populate it. The LOAD DATA and INSERT statements are useful for this.

Suppose that your pet records can be described as shown here. (Observe that MySQL expects dates in 'YYYY-MM-DD'format; this may be different from what you are used to.)