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, 1 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 5.7.21, for Linux (i686) using EditLine wrapper Connection id: 13 Current database: Current user: [email protected] SSL: Not in use Current pager: stdout Using outfile: '' Using delimiter: ; Server version: 5.7.21 MySQL Community Server (GPL) Protocol version: 10 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: 5 hours 28 min 6 sec Threads: 1 Questions: 211 Slow queries: 0 Opens: 123 Flush tables: 1 Open tables: 116 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 | +--------+ 1 row in set (0.00 sec)
mysql> desc t_users; +----------+-------------+------+-----+-------------------+----------------+ | Field | Type | Null | Key | Default | Extra | +----------+-------------+------+-----+-------------------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | name | varchar(20) | NO | | NULL | | | owner | varchar(20) | NO | | NULL | | | descinfo | varchar(50) | YES | | NULL | | | sex | char(1) | NO | | 1 | | | birth | date | YES | | NULL | | | death | date | YES | | NULL | | | addtime | datetime | YES | | CURRENT_TIMESTAMP | | +----------+-------------+------+-----+-------------------+----------------+ 8 rows in set (0.00 sec)
【删除数据库】
mysql> drop database testdb; Query OK, 0 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 '123456'; Query OK, 0 rows affected, 1 warning (0.00 sec) mysql> flush privileges; Query OK, 0 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 | +-----------+---------------+-------------------------------------------+ 5 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(11) not null auto_increment, name varchar(20) not null comment '姓名', owner varchar(20) not null, descinfo varchar(50), sex char(1) not null default '1', 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, 0 rows affected, 1 warning (0.00 sec) Query OK, 0 rows affected (0.02 sec) mysql> show tables; +------------------+ | Tables_in_testdb | +------------------+ | t_users | +------------------+ 1 row in set (0.00 sec) mysql> desc t_users; +----------+-------------+------+-----+-------------------+----------------+ | Field | Type | Null | Key | Default | Extra | +----------+-------------+------+-----+-------------------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | name | varchar(20) | NO | | NULL | | | owner | varchar(20) | NO | | NULL | | | descinfo | varchar(50) | YES | | NULL | | | sex | char(1) | NO | | 1 | | | birth | date | YES | | NULL | | | death | date | YES | | NULL | | | addtime | datetime | YES | | CURRENT_TIMESTAMP | | +----------+-------------+------+-----+-------------------+----------------+ 8 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, 1 row affected (0.01 sec) mysql> select t.* from t_users t; +----+----------+-----------+---------------------+-----+------------+------------+---------------------+ | id | name | owner | descinfo | sex | birth | death | addtime | +----+----------+-----------+---------------------+-----+------------+------------+---------------------+ | 1 | php webs | test webs | test ok next boooks | 1 | 2018-04-20 | 2018-04-20 | 2018-04-20 16:40:59 | +----+----------+-----------+---------------------+-----+------------+------------+---------------------+ 1 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() | +-----------+------------+ | 5.7.21 | 2018-04-20 | +-----------+------------+ 1 row in set (0.00 sec)
mysql> select version(),current_date; +-----------+--------------+ | version() | current_date | +-----------+--------------+ | 5.7.21 | 2018-04-20 | +-----------+--------------+ 1 row in set (0.00 sec)
now(): 函数查询当前时间
mysql> select version(),now(); +-----------+---------------------+ | version() | now() | +-----------+---------------------+ | 5.7.21 | 2018-04-20 15:53:04 | +-----------+---------------------+ 1 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 | +----+------------+--------------+-----------------+ | 1 | 学习 PHP | 菜鸟教程 | 2018-04-11 | | 31 | PHP webs | Doe | 2018-04-16 | +----+------------+--------------+-----------------+ 2 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)=11; +----+------------+--------------+-----------------+ | id | title | author | submission_date | +----+------------+--------------+-----------------+ | 1 | 学习 PHP | 菜鸟教程 | 2018-04-11 | +----+------------+--------------+-----------------+ 1 row in set (0.01 sec) mysql> select t.* from t_users t where month(t.submission_date)=4; +----+------------+--------------+-----------------+ | id | title | author | submission_date | +----+------------+--------------+-----------------+ | 1 | 学习 PHP | 菜鸟教程 | 2018-04-11 | | 31 | PHP webs | Doe | 2018-04-16 | +----+------------+--------------+-----------------+ 2 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()),12)+1 as nextmonth; +-----------+ | nextmonth | +-----------+ | 5 | +-----------+ 1 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()),12)+1 ;
1 is null 返回false；
1 is not null 返回 true；
mysql> select 1 is not null; +---------------+ | 1 is not null | +---------------+ | 1 | +---------------+ 1 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 | 5 | | GOGGGOOK | 2 | | GOOOK | 1 | +----------+-------------+ 3 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) | +---------+ | 17 | +---------+ 1 row in set (0.00 sec)
【统计每天访问量】
mysql> select t.* from t1 t; +------+-------+------+ | year | month | day | +------+-------+------+ | 2000 | 1 | 1 | | 2000 | 1 | 20 | | 2000 | 1 | 30 | | 2000 | 2 | 2 | | 2000 | 2 | 22 | | 2000 | 2 | 23 | | 2000 | 2 | 22 | +------+-------+------+ 7 rows in set (0.01 sec) mysql> select year,month,bit_count(bit_or(1<<day)) as days from t1 group by year,month; +------+-------+------+ | year | month | days | +------+-------+------+ | 2000 | 1 | 3 | | 2000 | 2 | 3 | +------+-------+------+ 2 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 | +----+----------+--------+-----------------+ | 31 | PHP webs | Doe | 2018-04-16 | +----+----------+--------+-----------------+ 1 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 | +----+------------+--------------+-----------------+ | 1 | 学习 PHP | 菜鸟教程 | 2018-04-11 | +----+------------+--------------+-----------------+ 1 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 | +----+-------+--------+-----------------+ | 32 | John | Doe | 2018-04-20 | | 33 | John | Doe | 2018-04-20 | | 34 | John | Doe | 2018-04-20 | | 35 | John | Doe | 2018-04-20 | | 36 | John | Doe | 2018-04-20 | | 37 | John | Doe | 2018-04-20 | +----+-------+--------+-----------------+ 6 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 | +----+----------+--------+-----------------+ | 31 | PHP webs | Doe | 2018-04-16 | +----+----------+--------+-----------------+ 1 row in set (0.00 sec)
查询以s结尾：
mysql> select * from t_users where title regexp 's$'; +----+----------+--------+-----------------+ | id | title | author | submission_date | +----+----------+--------+-----------------+ | 31 | PHP webs | Doe | 2018-04-16 | +----+----------+--------+-----------------+ 1 row in set (0.00 sec)
查询title包含e字符的：
mysql> select * from t_users where title regexp 'e'; +----+------------+----------+-----------------+ | id | title | author | submission_date | +----+------------+----------+-----------------+ | 31 | PHP webs | Doe | 2018-04-16 | | 38 | nexJohn | Doe | 2018-04-20 | | 39 | nexJohn123 | Doe baok | 2018-04-20 | +----+------------+----------+-----------------+ 3 rows in set (0.00 sec)
利用...匹配查询4个字符的名称：如查询以J开头的 并且是...表示三个字符
如：要找到只包含3个字符的名字，使用“^"和“$"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...$'; +----+-------+--------+-----------------+ | id | title | author | submission_date | +----+-------+--------+-----------------+ | 32 | John | Doe | 2018-04-20 | | 33 | John | Doe | 2018-04-20 | | 34 | John | Doe | 2018-04-20 | | 35 | John | Doe | 2018-04-20 | | 36 | John | Doe | 2018-04-20 | | 37 | John | Doe | 2018-04-20 | +----+-------+--------+-----------------+ 6 rows in set (0.00 sec)
利用{n} ；n表示重复次数来替换上面的语句查询：
mysql> select * from t_users where title regexp '^.{4}$'; +----+-------+--------+-----------------+ | id | title | author | submission_date | +----+-------+--------+-----------------+ | 32 | John | Doe | 2018-04-20 | | 33 | John | Doe | 2018-04-20 | | 34 | John | Doe | 2018-04-20 | | 35 | John | Doe | 2018-04-20 | | 36 | John | Doe | 2018-04-20 | | 37 | John | Doe | 2018-04-20 | +----+-------+--------+-----------------+ 6 rows in set (0.00 sec)