mysql 5.7 增删改查及别名的用法

1.启动和停止服务

一）启动和停止

#启动服务：
$sudo service mysql start
#停止服务：
$sudo service mysql stop 

二）创建和选择数据库

【创建数据库】

mysql> create database testdb;
Query OK,  row affected (0.01 sec)

mysql> create database testdb default character set 'utf8';
Query OK, 1 row affected (0.00 sec)

status命令查看数据库状态：

mysql> status;
--------------
mysql  Ver 14.14 Distrib 5.7., for Linux (i686) using  EditLine wrapper

Connection id:
Current database:
Current user:        root@localhost
SSL:            Not in use
Current pager:        stdout
Using outfile:        ''
Using delimiter:    ;
Server version:        5.7. MySQL Community Server (GPL)
Protocol version:
Connection:        Localhost via UNIX socket
Server characterset:    latin1
Db     characterset:    latin1
Client characterset:    utf8
Conn.  characterset:    utf8
UNIX socket:        /var/run/mysqld/mysqld.sock
Uptime:             hours  min  sec

Threads:   Questions:   Slow queries:   Opens:   Flush tables:   Open tables:   Queries per second avg: 0.010

【选择数据库】

mysql> use testdb;
Database changed

【查看当前登录的数据库】

mysql> select database() mydb;
+--------+
| mydb   |
+--------+
| testdb |
+--------+
 row in set (0.00 sec)

mysql> desc t_users;
+----------+-------------+------+-----+-------------------+----------------+
| Field    | Type        | Null | Key | Default           | Extra          |
+----------+-------------+------+-----+-------------------+----------------+
| id       | int()     | NO   | PRI | NULL              | auto_increment |
| name     | varchar() | NO   |     | NULL              |                |
| owner    | varchar() | NO   |     | NULL              |                |
| descinfo | varchar() | YES  |     | NULL              |                |
| sex      | char()     | NO   |     |                  |                |
| birth    | date        | YES  |     | NULL              |                |
| death    | date        | YES  |     | NULL              |                |
| addtime  | datetime    | YES  |     | CURRENT_TIMESTAMP |                |
+----------+-------------+------+-----+-------------------+----------------+
 rows in set (0.00 sec)

【删除数据库】

mysql> drop database testdb;
Query OK,  rows affected (0.00 sec)

【创建用户和分配权限】

mysql> grant all privileges  on testdb.* to 'test2'@'localhost' identified by '';
Query OK,  rows affected,  warning (0.00 sec)

mysql> flush privileges;
Query OK,  rows affected (0.00 sec)

mysql> select host,user,authentication_string from user;
+-----------+---------------+-------------------------------------------+
| host      | user          | authentication_string                     |
+-----------+---------------+-------------------------------------------+
| %         | root          | *9AAE89836D1D658A0BED88FEB96A3DFF84C94D77 |
| %         | mysql.session | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
| %         | mysql.sys     | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
| localhost | test          | *6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9 |
| localhost | test2         | *6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9 |
+-----------+---------------+-------------------------------------------+
 rows in set (0.00 sec)

【创建表】

从源文件引入创建：假设有个sql.txt

DROP TABLE IF EXISTS t_users;
create table t_users (
id int() not null auto_increment,
name varchar() not null comment '姓名',
owner varchar() not null,
descinfo varchar(),
sex char() not null default '',
birth date comment '生日',
death date,
addtime datetime NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
primary key (id)
);

然后执行：

mysql> source ./sql.txt;
Query OK,  rows affected,  warning (0.00 sec)

Query OK,  rows affected (0.02 sec)

mysql> show tables;
+------------------+
| Tables_in_testdb |
+------------------+
| t_users          |
+------------------+
 row in set (0.00 sec)

mysql> desc t_users;
+----------+-------------+------+-----+-------------------+----------------+
| Field    | Type        | Null | Key | Default           | Extra          |
+----------+-------------+------+-----+-------------------+----------------+
| id       | int()     | NO   | PRI | NULL              | auto_increment |
| name     | varchar() | NO   |     | NULL              |                |
| owner    | varchar() | NO   |     | NULL              |                |
| descinfo | varchar() | YES  |     | NULL              |                |
| sex      | char()     | NO   |     |                  |                |
| birth    | date        | YES  |     | NULL              |                |
| death    | date        | YES  |     | NULL              |                |
| addtime  | datetime    | YES  |     | CURRENT_TIMESTAMP |                |
+----------+-------------+------+-----+-------------------+----------------+
 rows in set (0.00 sec)

mysql> insert into t_users (name,owner,descinfo,birth,death) values ('php webs','test webs','test ok next boooks',curdate(),curdate());
Query OK,  row affected (0.01 sec)

mysql> select t.* from t_users t;
+----+----------+-----------+---------------------+-----+------------+------------+---------------------+
| id | name     | owner     | descinfo            | sex | birth      | death      | addtime             |
+----+----------+-----------+---------------------+-----+------------+------------+---------------------+
|   | php webs | test webs | test ok next boooks |    | -- | -- | -- :: |
+----+----------+-----------+---------------------+-----+------------+------------+---------------------+
 row in set (0.00 sec)

2.删掉时候用别名

delete t from t_users t where t.title='John';

3.查询及排序

默认asc升序 降序desc

SELECT name, birth FROM pet ORDER BY birth

结果：

查询当前时间和mysql版本函数 curdate() 和 current_date：

mysql> select version(),curdate();
+-----------+------------+
| version() | curdate()  |
+-----------+------------+
| 5.7.    | -- |
+-----------+------------+
 row in set (0.00 sec)

mysql> select version(),current_date;
+-----------+--------------+
| version() | current_date |
+-----------+--------------+
| 5.7.    | --   |
+-----------+--------------+
 row in set (0.00 sec)

now(): 函数查询当前时间

mysql> select version(),now();
+-----------+---------------------+
| version() | now()               |
+-----------+---------------------+
| 5.7.    | -- :: |
+-----------+---------------------+
 row in set (0.00 sec)

TIMESTAMPDIFF (year,birth,curdate())：日期计算使用 函数计算 查询年龄：

mysql> SELECT name, birth, CURDATE(),TIMESTAMPDIFF(YEAR,birth,CURDATE()) AS age FROM pet;

结果：

 is not null 查询不为空的数据：

mysql> select t.* from t_users t where t.title is not null;
+----+------------+--------------+-----------------+
| id | title      | author       | submission_date |
+----+------------+--------------+-----------------+
|   | 学习 PHP   | 菜鸟教程     | --      |
|  | PHP webs   | Doe          | --      |
+----+------------+--------------+-----------------+
 rows in set (0.00 sec)

day()  和month()函数的使用：查询指定日期的数据：

mysql> select t.* from t_users t where day(t.submission_date)=;
+----+------------+--------------+-----------------+
| id | title      | author       | submission_date |
+----+------------+--------------+-----------------+
|   | 学习 PHP   | 菜鸟教程     | --      |
+----+------------+--------------+-----------------+
 row in set (0.01 sec)

mysql> select t.* from t_users t where month(t.submission_date)=;
+----+------------+--------------+-----------------+
| id | title      | author       | submission_date |
+----+------------+--------------+-----------------+
|   | 学习 PHP   | 菜鸟教程     | --      |
|  | PHP webs   | Doe          | --      |
+----+------------+--------------+-----------------+
 rows in set (0.00 sec)

mod(n,m) 取余函数的使用；

查询下一个月：

mysql> select mod(month(curdate()),)+ as nextmonth;
+-----------+
| nextmonth |
+-----------+
|          |
+-----------+
 row in set (0.00 sec)

如：想要查询下一个月过生日的人；

mysql> select t.* from t_users where t.month(birth) =  mod(month(curdate()),)+ ;

1 is null 返回false；

1 is not null 返回 true；

mysql> select  is not null;
+---------------+
|  is not null |
+---------------+
|              |
+---------------+
 row in set (0.00 sec)

利用count()函数统计数据 以owner分组 group by

mysql> select owner,count(name) from t_users where name like 'C%' group by owner;
+----------+-------------+
| owner    | count(name) |
+----------+-------------+
| C webs   |            |
| GOGGGOOK |            |
| GOOOK    |            |
+----------+-------------+
 rows in set (0.00 sec)

max(col)：查询某列的最大值

mysql> select max(id) from t_users;
+---------+
| max(id) |
+---------+
|       |
+---------+
 row in set (0.00 sec)

【统计每天访问量】

mysql> select t.* from t1 t;
+------+-------+------+
| year | month | day  |
+------+-------+------+
|  |      |     |
|  |      |    |
|  |      |    |
|  |      |     |
|  |      |    |
|  |      |    |
|  |      |    |
+------+-------+------+
 rows in set (0.01 sec)

mysql> select year,month,bit_count(bit_or(<<day)) as days from t1 group by year,month;
+------+-------+------+
| year | month | days |
+------+-------+------+
|  |      |     |
|  |      |     |
+------+-------+------+
 rows in set (0.00 sec)

4.Mysql使用正则表达式匹配模糊查询 like的使用

Mysql提供了一个标准的SQL模式匹配，和基于扩展的正则表达式的模式匹配Unix工具（如vi,grep,sed)一样。
SQL模式匹配可以使用：

“_“来匹配任意单个字符，

”％“可以用来匹配任意数量（包含0个字符）的字符。

在MySQL中，SQL模式匹配的大小写默认是不敏感的，以下有一些例子，当你在使用SQL模式时，不要使用＝或<>，而是使用LIKE或NOTLIKE。

要找到P%开头的名字：

mysql> select t.* from t_users t where t.title like 'P%'
    -> ;
+----+----------+--------+-----------------+
| id | title    | author | submission_date |
+----+----------+--------+-----------------+
|  | PHP webs | Doe    | --      |
+----+----------+--------+-----------------+
 row in set (0.00 sec)

查询以%P结尾的名字：

mysql> select t.* from t_users t where t.title like '%PHP';
+----+------------+--------------+-----------------+
| id | title      | author       | submission_date |
+----+------------+--------------+-----------------+
|   | 学习 PHP   | 菜鸟教程     | --      |
+----+------------+--------------+-----------------+
 row in set (0.00 sec)

使用“_”匹配 4个字符的名字：

mysql> select t.* from t_users t where t.title like '____';
+----+-------+--------+-----------------+
| id | title | author | submission_date |
+----+-------+--------+-----------------+
|  | John  | Doe    | --      |
|  | John  | Doe    | --      |
|  | John  | Doe    | --      |
|  | John  | Doe    | --      |
|  | John  | Doe    | --      |
|  | John  | Doe    | --      |
+----+-------+--------+-----------------+
 rows in set (0.00 sec)

5.利用正则表达式REGEXP 和 NOT REGEXP

MySQL提供的其他模式匹配类型是使用扩展的正则表达式，当你使用这个类型来测试一个匹配，
要使用REGEXP和NOT REGEXP操作（或者RLIKE和NOT RLIKE，他们是同意詞）。
下面的列表描述了一些扩展正则表达式的特征：

"."匹配任意单个字符.

[a-z]:单个字符匹配类"[...]"匹配括号里的任意字符，例如，"[abc]"匹配"a","b",或"c",要指定字符范围，可以使用"-",
例如，[a-z] 匹配任意字母，而[0-9]匹配任意数字。

"*" 匹配0个或多个在它前面的东西。例如，"x*" 匹配任意个x字符，"[0-9]*"匹配任意个数字，".*"匹配任意个字符。
一个REGEXP模式匹配成功的条件是，模式在测试值中的任意地方匹配即可。
（这与LIKE模式匹配不同，LIKE模式匹配成功需要匹配整个值）。
"^" 开头作为模式匹配或用
"$" 作为模式的结尾。

为了验证扩展的正则表达式是如何工作的，在这使用REGEXP对前面使用LIKE查询进行重写。

查询以P开头：

mysql> select * from t_users where title regexp '^P';
+----+----------+--------+-----------------+
| id | title    | author | submission_date |
+----+----------+--------+-----------------+
|  | PHP webs | Doe    | --      |
+----+----------+--------+-----------------+
 row in set (0.00 sec)

查询以s结尾：

mysql> select * from t_users where title regexp 's$';
+----+----------+--------+-----------------+
| id | title    | author | submission_date |
+----+----------+--------+-----------------+
|  | PHP webs | Doe    | --      |
+----+----------+--------+-----------------+
 row in set (0.00 sec)

查询title包含e字符的：

mysql> select * from t_users where title regexp 'e';
+----+------------+----------+-----------------+
| id | title      | author   | submission_date |
+----+------------+----------+-----------------+
|  | PHP webs   | Doe      | --      |
|  | nexJohn    | Doe      | --      |
|  | nexJohn123 | Doe baok | --      |
+----+------------+----------+-----------------+
 rows in set (0.00 sec)

利用...匹配查询4个字符的名称：如查询以J开头的 并且是...表示三个字符

如：要找到只包含3个字符的名字，使用“^"和“$"来匹配名字的开头和结尾，且放3个“."在中间

mysql> select * from t_users where title regexp '^J...$';
+----+-------+--------+-----------------+
| id | title | author | submission_date |
+----+-------+--------+-----------------+
|  | John  | Doe    | --      |
|  | John  | Doe    | --      |
|  | John  | Doe    | --      |
|  | John  | Doe    | --      |
|  | John  | Doe    | --      |
|  | John  | Doe    | --      |
+----+-------+--------+-----------------+
 rows in set (0.00 sec)

利用{n} ；n表示重复次数来替换上面的语句查询：

mysql> select * from t_users where title regexp '^.{4}$';
+----+-------+--------+-----------------+
| id | title | author | submission_date |
+----+-------+--------+-----------------+
|  | John  | Doe    | --      |
|  | John  | Doe    | --      |
|  | John  | Doe    | --      |
|  | John  | Doe    | --      |
|  | John  | Doe    | --      |
|  | John  | Doe    | --      |
+----+-------+--------+-----------------+
 rows in set (0.00 sec)