python
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# 连接数据库
mysql -u root -p
#u是用户名 p需要用密码登录数据库
# 查看数据库
show database;
# 选择数据库
use database_name;
#查看数据库当中的table表
show tables;
#创建数据库
create database examination;
#删除数据库
drop table examination;
python
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#创建表
create TABLE house (
id int(11) unsigned NOT NULL AUTO_INCREMENT,
price decimal(10,2) DEFAULT NULL,
unit varchar(255) COLLATE utf8mb4_general_ci DEFAULT NULL,
area varchar(255) COLLATE utf8mb4_general_ci DEFAULT NULL,
direction varchar(255) COLLATE utf8mb4_general_ci DEFAULT NULL,
floor varchar(255) COLLATE utf8mb4_general_ci DEFAULT NULL,
layout varchar(255) COLLATE utf8mb4_general_ci DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci
#查看表结构
desc house
#查看建表语句
show create table house
python
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# 创建表
create table class(
id int(11) unsigned not null auto_increment,
name varchar(80) not null,
primary key(id)
);
create table exam(
id int(11) unsigned not null auto_increment,
name varchar(80) not null,
primary key(id)
);
create table score(
id int(11) unsigned not null auto_increment,
student_id int(11) not null,
subject_id int(11) not null,
exam_id int(11) not null,
score int(11) not null,
primary key(id)
);
create table student(
id int(11) unsigned not null auto_increment,
class_id int(11) not null,
sex char(10) not null,
name varchar(80) not null,
primary key(id)
);
create table subject(
id int(11) unsigned not null auto_increment,
name varchar(80) not null,
primary key(id)
);
#插入数据
insert into class(name)
values('高二九班');
#修改数据
update class set name = '环境18-1'
where id = '3';
使用Python操作数据库
python
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import pymysql
python
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DATABASE = {
'host':'127.0.0.1',
'database':'examination',
'user':'root',
'password':'123qwe'
# 'charset':'utf8mb4'
}
#连接到数据库
# conn = pymysql.connect(host = '127.0.0.1',user = 'root',password = '123qwe', db = 'examination')
conn = pymysql.connect(**DATABASE)
查询操作
python
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#创建游标
cursor = conn.cursor()
#执行sql查询
sql = "select * from class;"
cursor.execute(sql)
#获取查询结果
results = cursor.fetchall()
#打印查询结果
for row in results:
print(row)
插入操作
python
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#创建游标
cursor = conn.cursor()
#执行sql插入
sql = "insert into class(name) values('高一二十一班');"
cursor.execute(sql)
sql = "insert into class(name) values('信息18-2');"
cursor.execute(sql)
#提交sql插入语句
conn.commit()
查询操作
python
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#创建游标
cursor = conn.cursor()
#执行sql查询
sql = "select * from class;"
cursor.execute(sql)
#获取查询结果
results = cursor.fetchall()
#打印查询结果
for row in results:
print(row)
(1, '高二九班')
(2, '高三十七班')
(3, '环境18-1')
(4, '高一二十一班')
(5, '信息18-2')
更新操作
python
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#创建游标
cursor = conn.cursor()
#执行sql更新
sql = "update class set name = '初二十四班' where id = 4;"
cursor.execute(sql)
#提交sql更新语句
conn.commit()
查询操作
python
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#创建游标
cursor = conn.cursor()
#执行sql查询
sql = "select * from class;"
cursor.execute(sql)
#获取查询结果
results = cursor.fetchall()
#打印查询结果
for row in results:
print(row)
(1, '高二九班')
(2, '高三十七班')
(3, '环境18-1')
(4, '初二十四班')
(5, '信息18-2')
删除操作
python
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#创建游标
cursor = conn.cursor()
#执行sql删除
sql = "delete from class where id = 4;"
cursor.execute(sql)
#提交sql删除语句
conn.commit()
查询操作
python
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#创建游标
cursor = conn.cursor()
#执行sql查询
sql = "select * from class;"
cursor.execute(sql)
#获取查询结果
results = cursor.fetchall()
#打印查询结果
for row in results:
print(row)
(1, '高二九班')
(2, '高三十七班')
(3, '环境18-1')
(5, '信息18-2')
更新操作
python
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#创建游标
cursor = conn.cursor()
#执行sql更新
sql = "update class set name = '高一二十一班',id = 4 where id = 5;"
cursor.execute(sql)
#提交sql更新语句
conn.commit()
查询操作
python
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#创建游标
cursor = conn.cursor()
#执行sql查询
sql = "select * from class;"
cursor.execute(sql)
#获取查询结果
results = cursor.fetchall()
#打印查询结果
for row in results:
print(row)
(1, '高二九班')
(2, '高三十七班')
(3, '环境18-1')
(4, '高一二十一班')
python
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#关闭游标和连接
cursor.close()
conn.close()
python
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# 捕捉异常
try:
a = 10
b = a+'hello'
except TypeError as e:
print(e)
unsupported operand type(s) for +: 'int' and 'str'
python
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a = 10
b = a+'hello'
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-71-00244769db33> in <module>
1 a = 10
----> 2 b = a+'hello'
TypeError: unsupported operand type(s) for +: 'int' and 'str'
python
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#实现回滚操作（数据库操作回滚失败）
try：
#执行sql查询
sql = "insert into class(name) values('管科24-1');"
#创建游标
cursor = conn.cursor()
#执行sql
cursor.execute(sql)
#do something
error = 10 + 'hello'
#提交sql插入语句
conn.commit()
except Exception as e:
print(e)
conn.rollback()