python-learning-第二季-数据库编程

https://www.bjsxt.com/down/8468.html

代码实现：

#coding:utf-

#导入模块

import sqlite3

#创建connect连接

con = sqlite3.connect('./sqlitedb/demo.db')

print(con) #查看连接是否成功生成,<sqlite3.Connection object at 0x10ae6b3b0>

#创建游标对象

cur = con.cursor()

#编写创建表的sql语句

sql = '''create table t_person(

        pno INTEGER primary key autoincrement,

        pname VARCHAR not null,

        age INTEGER

    )'''

try:

    #执行说sql语句

    cur.execute(sql)

    print('创建表成功')

except Exception as e:

    print(e)

finally:

    #关闭游标

    cur.close()

    #关闭连接

    con.close()

/Users/user/PycharmProjects/python3/venv/bin/python /Users/user/PycharmProjects/python3/test.py

<sqlite3.Connection object at 0x106ded3b0>

创建表成功

操作sqlite3数据库插入数据

#coding:utf-

#导入模块

import sqlite3

#创建connect连接

con = sqlite3.connect('./sqlitedb/demo.db')

print(con) #查看连接是否成功生成,<sqlite3.Connection object at 0x10ae6b3b0>

#创建游标对象

cur = con.cursor()

#pno是自增长的，可不赋值

#（?,?）表示占位符，在执行时会传入

sql = 'insert into t_person(pname, age) values (?,?)'

try:

    #执行说sql语句

    cur.execute(sql, ('张三', ))

    #提交事务

    con.commit()

    print('插入成功')

except Exception as e:

    print(e)

    #回滚

    con.rollback()

    print('插入数据失败')

finally:

    #关闭游标

    cur.close()

    #关闭连接

    con.close()

/Users/user/PycharmProjects/python3/venv/bin/python /Users/user/PycharmProjects/python3/test.py

<sqlite3.Connection object at 0x10c6ac3b0>

插入成功

Process finished with exit code

插入多条数据：

#coding:utf-

#导入模块

import sqlite3

#创建connect连接

con = sqlite3.connect('./sqlitedb/demo.db')

print(con) #查看连接是否成功生成,<sqlite3.Connection object at 0x10ae6b3b0>

#创建游标对象

cur = con.cursor()

#pno是自增长的，可不赋值

#（?,?）表示占位符，在执行时会传入

sql = 'insert into t_person(pname, age) values (?,?)'

try:

    #执行插入多条sql语句

    cur.executemany(sql, [('小李', ), ('小明', ), ('小雨', )])

    #提交事务

    con.commit()

    print('插入多条数据成功')

except Exception as e:

    print(e)

    #回滚

    con.rollback()

    print('插入多条数据失败')

finally:

    #关闭游标

    cur.close()

    #关闭连接

    con.close()

/Users/user/PycharmProjects/python3/venv/bin/python /Users/user/PycharmProjects/python3/test.py

<sqlite3.Connection object at 0x1019fd3b0>

插入多条数据成功

Process finished with exit code

操作sqlite3数据库查询数据

#coding:utf-

#导入模块

import sqlite3

#创建connect连接

con = sqlite3.connect('./sqlitedb/demo.db')

print(con) #查看连接是否成功生成,<sqlite3.Connection object at 0x10ae6b3b0>

#创建游标对象

cur = con.cursor()

sql = 'select * from t_person'

try:

    #执行查询所有sql内容

    cur.execute(sql)

    #获取所有数据

    person_all = cur.fetchall()

    #返回的是数组

    #遍历输出

    for p in person_all:

        print(p)

except Exception as e:

    print(e)

    print('查询失败')

finally:

    #关闭游标

    cur.close()

    #关闭连接

    con.close()

/Users/user/PycharmProjects/python3/venv/bin/python /Users/user/PycharmProjects/python3/test.py

<sqlite3.Connection object at 0x105f903b0>

(, '张三', )

(, '小李', )

(, '小明', )

(, '小雨', )

Process finished with exit code

查询一条：

#coding:utf-

#导入模块

import sqlite3

#创建connect连接

con = sqlite3.connect('./sqlitedb/demo.db')

print(con) #查看连接是否成功生成,<sqlite3.Connection object at 0x10ae6b3b0>

#创建游标对象

cur = con.cursor()

sql = 'select * from t_person'

try:

    #执行查询所有数据sql语句

    cur.execute(sql)

    #获取一条数据

    person = cur.fetchone()

    print(person)

except Exception as e:

    print(e)

    print('查询失败')

finally:

    #关闭游标

    cur.close()

    #关闭连接

    con.close()

/Users/user/PycharmProjects/python3/venv/bin/python /Users/user/PycharmProjects/python3/test.py

<sqlite3.Connection object at 0x1092793b0>

(, '张三', )

Process finished with exit code

修改数据：

#coding:utf-

#导入模块

import sqlite3

#创建connect连接

con = sqlite3.connect('./sqlitedb/demo.db')

print(con) #查看连接是否成功生成,<sqlite3.Connection object at 0x10ae6b3b0>

#创建游标对象

cur = con.cursor()

sql = 'update t_person set pname=? where pno=?'

try:

    #执行修改sql语句

    cur.execute(sql,('张四',))

    #提交事务

    con.commit()

    print('修改成功')

except Exception as e:

    print(e)

    #回滚

    con.rollback()

    print('修改失败')

finally:

    #关闭游标

    cur.close()

    #关闭连接

    con.close()

/Users/user/PycharmProjects/python3/venv/bin/python /Users/user/PycharmProjects/python3/test.py

<sqlite3.Connection object at 0x10d4bb3b0>

修改成功

Process finished with exit code

查询可见修改成功：

/Users/user/PycharmProjects/python3/venv/bin/python /Users/user/PycharmProjects/python3/test.py

<sqlite3.Connection object at 0x10ab113b0>

(, '张四', )

Process finished with exit code

删除数据：

#coding:utf-

#导入模块

import sqlite3

#创建connect连接

con = sqlite3.connect('./sqlitedb/demo.db')

print(con) #查看连接是否成功生成,<sqlite3.Connection object at 0x10ae6b3b0>

#创建游标对象

cur = con.cursor()

sql = 'delete from t_person where pno=?'

try:

    #执行删除sql语句

    cur.execute(sql,(,)) #元组仅有一个参数，必需有面加逗号，保证参数类型为元组

    #提交事务

    con.commit()

    print('删除成功')

except Exception as e:

    print(e)

    #回滚

    con.rollback()

    print('删除失败')

finally:

    #关闭游标

    cur.close()

    #关闭连接

    con.close()

/Users/user/PycharmProjects/python3/venv/bin/python /Users/user/PycharmProjects/python3/test.py

<sqlite3.Connection object at 0x101ebb3b0>

删除成功

Process finished with exit code

此时查看第一条数据为：

/Users/user/PycharmProjects/python3/venv/bin/python /Users/user/PycharmProjects/python3/test.py

<sqlite3.Connection object at 0x101e623b0>

(, '小李', )

Process finished with exit code

MySQL数据库的下载

我已经安装好了，这里省略，去官网下载即可，端口默认3306

安装对应的模块PyMySQL

以为之前的deeplearning中的可用在这，发现不行，所以就重新下载了：

(venv) (base) userdeMBP:python3 user$ pip install PyMySQL

Collecting PyMySQL

  Using cached https://files.pythonhosted.org/packages/ed/39/15045ae46f2a123019aa968dfcba0396c161c20f855f11dea6796bcaae95/PyMySQL-0.9.3-py2.py3-none-any.whl

Installing collected packages: PyMySQL

Successfully installed PyMySQL-0.9.

我已经下载好了

操作MySQL数据库创建表

先是创建了数据库python_db:

首先先连接：

#导入pymysql

import pymysql

#创建连接

con = pymysql.connect(host='localhost', user='root', password='user78', database='python_db', port=)

print(con)

成功连接：

/Users/user/PycharmProjects/python3/venv/bin/python /Users/user/PycharmProjects/python3/test.py

<pymysql.connections.Connection object at 0x103d3f6a0>

Process finished with exit code

#导入pymysql

import pymysql

#创建连接

con = pymysql.connect(host='localhost', user='root', password='user78', database='python_db', port=)

#创建游标对象

cur = con.cursor()

#编写创建表的sql，score总共三位，小数点占一位

sql = '''

    create table t_student(

        sno int primary key auto_increment,

        sname varchar() not null,

        age int(),

        score float(,)

    )

'''

try:

    #执行创建表的sql

    cur.execute(sql)

    print('创建成功')

except Exception as e:

    print(e)

    print('创建失败')

finally:

    #关闭游标

    cur.close()

    #关闭连接

    con.close()

/Users/user/PycharmProjects/python3/venv/bin/python /Users/user/PycharmProjects/python3/test.py

创建成功

Process finished with exit code

查看成功创建：

插入数据：

#导入pymysql

import pymysql

#创建连接

con = pymysql.connect(host='localhost', user='root', password='user78', database='python_db', port=)

#创建游标对象

cur = con.cursor()

#插入数据

sql = 'insert into t_student(sname, age, score) values(%s, %s, %s)'

try:

    #执行创建表的sql

    cur.execute(sql, ('王一', , ))

    #提交事务

    con.commit()

    print('插入成功')

except Exception as e:

    print(e)

    con.rollback()

    print('插入失败')

finally:

    #关闭游标

    cur.close()

    #关闭连接

    con.close()

/Users/user/PycharmProjects/python3/venv/bin/python /Users/user/PycharmProjects/python3/test.py

插入成功

Process finished with exit code

查看：

插入多条数据：

#导入pymysql

import pymysql

#创建连接

con = pymysql.connect(host='localhost', user='root', password='user78', database='python_db', port=)

#创建游标对象

cur = con.cursor()

#插入数据

sql = 'insert into t_student(sname, age, score) values(%s, %s, %s)'

temp = [('王二', , ), ('王三', , )]

try:

    #执行创建表的sql

    cur.executemany(sql, temp)

    #提交事务

    con.commit()

    print('插入成功')

except Exception as e:

    print(e)

    con.rollback()

    print('插入失败')

finally:

    #关闭游标

    cur.close()

    #关闭连接

    con.close()

/Users/user/PycharmProjects/python3/venv/bin/python /Users/user/PycharmProjects/python3/test.py

插入成功

Process finished with exit code

查看：

查询数据

#导入pymysql

import pymysql

#创建连接

con = pymysql.connect(host='localhost', user='root', password='user78', database='python_db', port=)

#创建游标对象

cur = con.cursor()

#查询多个数据

sql = 'select * from t_student where age >= 19'

try:

    #执行创建表的sql

    cur.execute(sql)

    students = cur.fetchall()

    print(students)

    print('查询成功')

except Exception as e:

    print(e)

    print('查询失败')

finally:

    #关闭游标

    cur.close()

    #关闭连接

    con.close()

/Users/user/PycharmProjects/python3/venv/bin/python /Users/user/PycharmProjects/python3/test.py

((, '王二', , 70.0), (, '王三', , 80.0))

查询成功

Process finished with exit code

查询：

#导入pymysql

import pymysql

#创建连接

con = pymysql.connect(host='localhost', user='root', password='user78', database='python_db', port=)

#创建游标对象

cur = con.cursor()

#查询多个数据

sql = 'select * from t_student where age >= 19'

try:

    #执行创建表的sql

    cur.execute(sql)

    students = cur.fetchall()

    for student in students:

        print(student[], end = ' ,')

        print(student[], end=' ,')

        print(student[], end=' ,')

        print(student[])

except Exception as e:

    print(e)

    print('查询失败')

finally:

    #关闭游标

    cur.close()

    #关闭连接

    con.close()

/Users/user/PycharmProjects/python3/venv/bin/python /Users/user/PycharmProjects/python3/test.py

 ,王二 , ,70.0

 ,王三 , ,80.0

Process finished with exit code

查询一个数据：

#导入pymysql

import pymysql

#创建连接

con = pymysql.connect(host='localhost', user='root', password='user78', database='python_db', port=)

#创建游标对象

cur = con.cursor()

#查询一个数据

sql = 'select * from t_student where age >= 19'

try:

    #执行创建表的sql

    cur.execute(sql)

    student = cur.fetchone()

    print(student)

except Exception as e:

    print(e)

    print('查询失败')

finally:

    #关闭游标

    cur.close()

    #关闭连接

    con.close()

/Users/user/PycharmProjects/python3/venv/bin/python /Users/user/PycharmProjects/python3/test.py

(, '王二', , 70.0)

Process finished with exit code

更新数据：

#导入pymysql

import pymysql

#创建连接

con = pymysql.connect(host='localhost', user='root', password='user78', database='python_db', port=3306)

#创建游标对象

cur = con.cursor()

#查询一个数据

sql = 'update t_student set sname=%s where sno =%s'

try:

    #执行创建表的sql

    cur.execute(sql, ('王五', 1))

    #提交事务

    con.commit()

    print('更新成功')

except Exception as e:

    print(e)

    con.rollback()

    print('更新失败')

finally:

    #关闭游标

    cur.close()

    #关闭连接

    con.close()

/Users/user/PycharmProjects/python3/venv/bin/python /Users/user/PycharmProjects/python3/test.py

更新成功

Process finished with exit code 0

查看：

删除数据：

#导入pymysql

import pymysql

#创建连接

con = pymysql.connect(host='localhost', user='root', password='user78', database='python_db', port=3306)

#创建游标对象

cur = con.cursor()

#查询一个数据

sql = 'delete from t_student  where sname =%s'

try:

    #执行创建表的sql

    cur.execute(sql, ('王五',))

    #提交事务

    con.commit()

    print('删除成功')

except Exception as e:

    print(e)

    con.rollback()

    print('删除失败')

finally:

    #关闭游标

    cur.close()

    #关闭连接

    con.close()

/Users/user/PycharmProjects/python3/venv/bin/python /Users/user/PycharmProjects/python3/test.py

更新成功

Process finished with exit code 0

查看：

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