1. 创建数据库相关命令:
首先,下载MySQL相关软件包:aptitude install mysql-server/mysql-client
MySQL中的root用户类似于Linux下的root用户,拥有最多高的权限,若操作不当会对数据造成严重的危害。因此,针对每一个应用程序创建对应的数据库及操作用户是一个好习惯。
mysql -u root -p + 回车 -u后跟用户名,-p表示需要密码登录,首次进入mysql用root用户(输入root用户账户的密码,这个密码要么是在安装过程中,要么是使用mysqladmin工具获得的。)。若进入失败,原因可能是原始密码未正确配置,可尝试用密码'root'登录。若仍报错,可参考如下解决方法:
http://www.cnblogs.com/kerrycode/p/4368312.html
http://blog.csdn.net/yangxt/article/details/17200611
mysql的相关安装目录可参考:
http://www.linuxidc.com/Linux/2014-10/108644.htm
下面命令尝试可用:
mysqladmin -u root -p password + 回车(若之前有密码,则会显示在password之后)
Enter password: 输入新密码(不可见)
mysql> STATUS(\s) - 列出当前mysql的相关状态信息
mysql> SHOW DATABASES; - 显示数据库列表
mysql> USE DB_name; - 选中数据库DB_name
mysql> SHOW TABLES; - 显示DB_name下的TABLES列表
mysql> CREATE DATABASE DB_name; - 创建一个新的数据库,当然,首先你应该以root用户登录,普通用户并没有创建数据库的权利
mysql> GRANT SELECT,INSERT,DELETE,UPDATE ON DB_name TO user_name IDENTIFIED
> by 'user_psd'; - 授予新用户user_name对于数据库DB_name的指定权限,登录密码user_psd。该用户拥有的权限:SELECT,INSERT,DELETE,UPDATE
mysql DB_name -u user_name -p - 用新创建的用户user_name登录数据库DB_name
mysql mytest -u root -p - 用root用户登录数据库DB_name,当我们需要为数据库DB_name创建新表时,需要root用户的权限,如下,创建新表的过程:
mysql> CREATE TABLE employees (
- > empid int not null, - 该字段列值非空
-> lastname varchar(30),
-> firstname varchar(30),
-> salary float,
-> primary key (empid)); - 该字段列值唯一,"primary key" 表示该列是表的主键, MySQL将自动索引该列
mysql> SHOW COLUMNS FROM employees; - 显示employees各字段信息(有时我们需要知道表的结构才能确定插入内容的格式)
mysql> SHOW CREATE TABLE employees; - 显示表employees的创建过程,同样可以查看其内部结构
mysql> INSERT INTO table VALUES (...); - 向表table插入一条信息,如:mysql> INSERT INTO employees VALUES (1, 'Blum', 'Rich', 25000.00);
若:mysql> INSERT INTO employees VALUES (1, 'Blum', 'Barbara', 45000.00);
则:ERROR 1062 (23000): Duplicate entry '1' for key 1
mysql> DELETE FROM employees WHERE empid = 1; - 删除empid = 1的那条信息
mysql> DELETE FROM employees; - 删除指定数据库表employees的所有项
mysql> SELECT * FROM employees; - 查询表employees的所有字段内容,SELECT为查询命令
mysql> SELECT datafields FROM table; - 查询字段列表datafields指定的内容(个字段间用“,”分割)。常用的三个过滤器修饰符如下:
WHERE:显示符合特定条件的数据行子集。如:mysql> SELECT * FROM employees WHERE salary > 40000;
ORDER BY:以指定顺序显示数据行。
LIMIT:只显示数据行的一个子集。
E.G. :
mysql> SELECT * FROM employees;
+-------+----------+-----------+--------+
| empid | lastname | firstname | salary |
+-------+----------+-----------+--------+
| 0 | ER | ZHANG | 4500 |
| 1 | SAN | ZHANG | 5500 |
| 2 | SI | ZHANG | 6500 |
| 3 | WU | ZHANG | 7500 |
| 4 | LIU | ZHANG | 8500 |
| 5 | QI | ZHANG | 9500 |
+-------+----------+-----------+--------+
mysql> SELECT lastname, salary FROM employees WHERE salary > 5000 && salary < 8000;
+----------+--------+
| lastname | salary |
+----------+--------+
| SAN | 5500 |
| SI | 6500 |
| WU | 7500 |
+----------+--------+
mysql> SELECT * FROM employees1 ORDER BY lastname (ASC/DECS); - 按字段lastname排序查询表employees1
mysql> SELECT * FROM employees1 WHERE salary LIKE '6%'; - 限制salary为数字6开头的项,LIKE字句可以代替“=”使用
mysql> exit/quit - 退出数据库软件
2. 新建数据库之后的相关操作:
ALTER:
mysql> ALTER TABLE table_name ...; - 创建表之后,有时我们需要对表的结构进行修改,就用这个作为命令头部
mysql> ALTER TABLE table_name RENAME (AS) table_new_name; - 表重命名
mysql> ALTER TABLE table_name ADD 列名 列数据类型 [AFTER 插入位置]; - 在表中新增一个字段信息
mysql> ALTER TABLE table_name CHANGE 列名称 列新名称 新数据类型; - 指定列重命名
mysql> ALTER TABLE table_name DROP 列名称; - 删除指定列
DROP:
mysql> DROP TABLE table_name; - 删除指定表
mysql> DROP DATABASE database_name; - 删除指定数据库
mysqladmin -u root -p drop database_name; - 同样可以使用mysqladmin命令在mysql软件之外删除指定数据库
UPDATE:
+-------+----------+-----------+--------+
| empid | lastname | firstname | salary |
+-------+----------+-----------+--------+ +-------+----------+-----------+--------+
| 5 | QI | ZHANG | 9500 | | 5 | QI | ZHANG | 9500 |
| 7 | BA | ZAHNG | 9500 | --> | 6 | BA | ZAHNG | 9500 |
+-------+----------+-----------+--------+ +-------+----------+-----------+--------+
mysql> UPDATE employees1
-> SET empid = 6
-> WHERE lastname = 'BA'; - 限定条件
3. 数据库表间数据复制:http://www.jb51.net/article/47562.htm
同一数据库表间复制:
INSERT (INTO) table1 select * from table2; - 完全复制(mysql测试可用)
INSERT (INTO) table1 select distinct * from table2; - 不复制重复纪录(mysql测试不可用)
INSERT (INTO) table1 select top 5 * from table2; - 前五条纪录(mysql测试不可用)
跨数据库表间复制:
INSERT (INTO) (current.)table1 select * from src_database.table2; - 完全复制
INSERT (INTO) (current.)table1 select distinct * from src_database.table2; - 不复制重复纪录
INSERT (INTO) (current.)table1 select top 5 * from src_database.table2; - 前五条纪录
若table1不存在,则首先应该创建表,并使其结构与src_database结构相同方可copy:
CREATE TABLE table1 LIKE (src_database.)table2; - +(src_database.)取决于是否在同一个数据库
INSERT table1 SELECT * FROM (src_database.)table2;
4. 数据库重命名的几种方法:http://www.cnblogs.com/allenhua/p/5393189.html
以方法四为例(mysqldump导出数据再导入):mytest -> mytest1
mysqldump -u root -p mytest > mytest_dump.SQL
mysql -u root -p -e "CREATE DATABASE mytest1"
mysql -u root -p mytest1 < mytest_dump.SQL
mysql -u root -p -e "DROP DATABASE mytest"
5. 数据库用户权限相关:
mysql> GRANT ALL PRIVILEGES ON mytest1.* TO test@localhost IDENTIFIED BY 'test'; - 授予用户test对于数据库mytest1的所有权限
mysql> GRANT SELECT, INSERT, DELETE,... ON mytest1.* TO test@localhost IDENTIFIED BY 'test'; - 授予用户test指定权限
mysql> DELETE FROM user WHERE user = 'test'; - 删除用户test
mysql> FLUSH PRIVILEGES; - 刷新各用户权限
mysql> select * from user; - 查询所有用户的权利
6. 多表查询:
mysql> SELECT salary FROM employees1
-> UNION (ALL)
-> SELECT salary FROM employees2; - 合并employees1与employees2两表salary结果,无重复。+(ALL)全列出可重复
+--------+
| salary |
+--------+
| 4500 |
| 5500 |
| 6500 |
| 7500 |
| 8500 |
| 9500 |
| 10500 |
| 11500 |
+--------+
三种JOIN查询方式:http://www.runoob.com/mysql/mysql-join.html
两个实例数据库结构如下:
mysql> SELECT * FROM tcount_tbl;
+---------------+--------------+
| runoob_author | runoob_count |
+---------------+--------------+
| 菜鸟教程 | 10 |
| RUNOOB.COM | 20 |
| Google | 22 |
+---------------+--------------+
mysql> SELECT * from runoob_tbl;
+-----------+---------------+---------------+-----------------+
| runoob_id | runoob_title | runoob_author | submission_date |
+-----------+---------------+---------------+-----------------+
| 1 | 学习 PHP | 菜鸟教程 | 2017-04-12 |
| 2 | 学习 MySQL | 菜鸟教程 | 2017-04-12 |
| 3 | 学习 Java | RUNOOB.COM | 2015-05-01 |
| 4 | 学习 Python | RUNOOB.COM | 2016-03-06 |
| 5 | 学习 C | FK | 2017-04-05 |
+-----------+---------------+---------------+-----------------+
INNER JOIN(内连接,或等值连接):获取两个表中字段匹配关系的记录
mysql> SELECT a.runoob_id, a.runoob_author, b.runoob_count FROM runoob_tbl a
-> INNER JOIN tcount_tbl b ON a.runoob_author = b.runoob_author;
等价于:
mysql> SELECT a.runoob_id, a.runoob_author, b.runoob_count FROM runoob_tbl a, tcount_tbl b
-> WHERE a.runoob_author = b.runoob_author;
+-------------+-----------------+----------------+
| a.runoob_id | a.runoob_author | b.runoob_count |
+-------------+-----------------+----------------+
--> | 1 | 菜鸟教程 | 10 |
--> | 2 | 菜鸟教程 | 10 |
| 3 | RUNOOB.COM | 20 |
| 4 | RUNOOB.COM | 20 |
+-------------+-----------------+----------------+
LEFT JOIN(左连接):获取左表所有记录,即使右表没有对应匹配的记录
mysql> SELECT a.runoob_id, a.runoob_author, b.runoob_count FROM runoob_tbl a
-> LEFT JOIN tcount_tbl b ON a.runoob_author = b.runoob_author;
+-------------+-----------------+----------------+
| a.runoob_id | a.runoob_author | b.runoob_count |
+-------------+-----------------+----------------+
--> | 1 | 菜鸟教程 | 10 |
--> | 2 | 菜鸟教程 | 10 |
| 3 | RUNOOB.COM | 20 |
| 4 | RUNOOB.COM | 20 |
| 5 | FK | NULL |
+-------------+-----------------+----------------+
RIGHT JOIN(右连接):与 LEFT JOIN 相反,用于获取右表所有记录,即使左表没有对应匹配的记录
mysql> SELECT a.runoob_id, a.runoob_author, b.runoob_count FROM runoob_tbl a
-> RIGHT JOIN tcount_tbl b ON a.runoob_author = b.runoob_author;
+-------------+-----------------+----------------+
| a.runoob_id | a.runoob_author | b.runoob_count |
+-------------+-----------------+----------------+
--> | 1 | 菜鸟教程 | 10 |
--> | 2 | 菜鸟教程 | 10 |
| 3 | RUNOOB.COM | 20 |
| 4 | RUNOOB.COM | 20 |
| NULL | NULL | 22 |
+-------------+-----------------+----------------+