mysql 常用命令,连接数据库,查看建表语句,批量导入数据,批量更新数据,连接查询

时间：2022-06-24 08:22:10

 

1.

1)MySQL 连接本地数据库,从cmd中进入mysql命令编辑器: root root分别为用户名和密码

mysql -uroot -proot

 

2)MySQL 连接本地数据库，用户名为“root”，密码“123”（注意：“-p”和“123” 之间不能有空格）

C:\>mysql -h localhost -u root -p123

 

2、MySQL 连接远程数据库（192.168.0.201），端口“3306”，用户名为“root”，密码“123”

C:\>mysql -h 192.168.0.201 -P 3306 -u root -p123

 3.查看mysql建表语句

命令：SHOW CREATE TABLE <table_name> 

　show create table employees;

| employees | CREATE TABLE `employees` ( `emp_no` int(11) NOT NULL, `birth_date` date NOT NULL, `first_name` varchar(14) NOT NULL, `last_name` varchar(16) NOT NULL, `gender` enum('M','F') NOT NULL, `hire_date` date NOT NULL, PRIMARY KEY (`emp_no`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 |

 ４.删除mysql 中的表

命令：drop table <表名>
mysql> drop table employees;
Query OK, 0 rows affected (0.15 sec)

 ５.仅查询employess表中的last_name,first_name和birthd_date三个数据

mysql> select concat(last_name,' ',first_name) as name,birth_date as birthday from employees;

６.

从其他数据库中指定的表中导入数据，employees.employees 导入前10条数据

mysql> insert into employees select * from employees.employees limit 10;

 7.批量更新数据

UPDATE `sys_invitation` SET `is_known`='0' WHERE (`to_id`='99996145289621');

8.连接查询

1).原生查询

select *,count(o.order_id) from customers as c ,orders as o where c.customer_id=o.customer_id and c.city='shanghai' group by c.customer_id having count(o.order_id)>0;

2).左连接

 select *,count(o.order_id) from customers as c left join orders as o on c.customer_id=o.customer_id where c.city='shanghai' group by c.customer_id having count(o.order_id)>0;

可把left join 改为inner join或者right join.

这里依赖两张表orders和customers.

orders建表语句:

CREATE TABLE `orders` (
  `order_id` varchar(10) NOT NULL,
  `customer_id` varchar(10) NOT NULL,
  PRIMARY KEY (`order_id`)
) ENGINE=InnoDB

插入数据:

mysql> insert into orders select 01332,111;
mysql> insert into orders select 01333,112;
mysql> insert into orders select 01334,113;
mysql> insert into orders select 01335,114;
mysql> insert into orders select 01336,111;
mysql> insert into orders select 01337,112;
mysql> insert into orders select 01338,115;

查看数据:

mysql> select * from orders;
+----------+-------------+
| order_id | customer_id |
+----------+-------------+
| 1332     | 111         |
| 1333     | 112         |
| 1334     | 113         |
| 1335     | 114         |
| 1336     | 111         |
| 1337     | 112         |
| 1338     | 115         |
+----------+-------------+
7 rows in set (0.00 sec)

customers建表语句:

 create table customers(customer_id varchar(10) not null, city varchar(10), PRIMARY KEY(customer_id) )ENGINE=INNODB;

customers插入数据:

mysql> insert into customers select 112,'shanghai';
mysql> insert into customers select 113,'shanghai';
mysql> insert into customers values(114,'beijing');
mysql> insert into customers values(115,'beijing');
mysql> insert into customers select 116,'hangzhou';

查看数据:

mysql> select * from customers;
+-------------+----------+
| customer_id | city     |
+-------------+----------+
| 111         | shanghai |
| 112         | shanghai |
| 113         | shanghai |
| 114         | beijing  |
| 115         | beijing  |
| 116         | hangzhou |
+-------------+----------+
6 rows in set (0.00 sec)

 

 9.更改数据库名称

alter table tb1 rename tb2;

将表tb1名称更改为tb2,使用rename命令

 

 10.查看mysql表大小和记录数

SHOW TABLE STATUS FROM 数据库名 LIKE 数据表名;
use testdb;
show table status from testdb like 'xuexi30';

 

11.

-- 修改表编码

ALTER TABLE `user` DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci

 

 

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