python-操作mysql数据库（增删改查）

# ### python 操作mysql 
import pymysql

# ### 1.基本语法
"""
# (1) 创建连接对象 host user password database 这四个参数必写
conn = pymysql.connect( host="127.0.0.1" , user="root" , password="123456" , database="db003" , charset="utf8" , port=3306 )
# (2) 创建游标对象 (用来操作数据库的增删改查)
cursor = conn.cursor()
print(cursor)
# (3) 执行sql语句
sql = "select * from employee"
# 执行查询语句返回的总条数
res = cursor.execute(sql)
print(res) 
# (4) 获取数据 fetchone 获取一条数据
# 返回的是元组,里面包含的是第一条的完整数据
res = cursor.fetchone()
print(res)
res = cursor.fetchone()
print(res)
res = cursor.fetchone()
print(res)
# (5) 释放游标对象
cursor.close()
# (6) 释放连接对象
conn.close()
"""

# ### 2.创建/删除 表操作
# conn = pymysql.connect(host="127.0.0.1",user="root",password="123456",database="db003")
# cursor = conn.cursor()

# 1.创建一张表
sql = """
create table t1(
id int unsigned primary key auto_increment,
first_name varchar(255) not null,
last_name varchar(255) not null,
sex tinyint not null,
age tinyint unsigned not null,
money float
);
"""
# res = cursor.execute(sql)
# print(res) # 无意义返回值

# 2.查询表结构
"""
sql = "desc t1"
res = cursor.execute(sql)
print(res) # 返回的是字段的个数
res = cursor.fetchone()
print(res)
res = cursor.fetchone()
print(res)
res = cursor.fetchone()
print(res)
"""
# 3.删除表
"""
try:
sql = "drop table t1"
res = cursor.execute(sql)
print(res) # 无意义返回值
except:
pass
"""

# ### 3.事务处理
"""pymysql 默认开启事务的,所有增删改的数据必须提交,否则默认回滚;rollback"""
conn = pymysql.connect(host="127.0.0.1",user="root",password="123456",database="db003")
cursor = conn.cursor()
sql1 = "begin"
sql2 = "update employee set emp_name='程咬钻石' where id = 18 "
sql3 = "commit"

res1 = cursor.execute(sql1)
res1 = cursor.execute(sql2)
res1 = cursor.execute(sql3)
# 一般在查询的时候,通过fetchone来获取结果
res1 = cursor.fetchone()
print(res1)

cursor.close()
conn.close()

# ### sql 注入攻击
import pymysql
# (1) sql注入的现象
''' 现象:绕开账号密码登录成功 '''
'''
user = input("请输入您的用户名>>>")
pwd  = input("请输入您的密码>>>")

conn = pymysql.connect(host="127.0.0.1" , user="root" , password="123456",database="db005")
cursor = conn.cursor()
sql1 = """
create table usr_pwd(
id int unsigned primary key auto_increment,
username varchar(255) not null,
password varchar(255) not null
)
"""
sql2 = "select * from usr_pwd where username='%s' and password='%s' " % (user,pwd)
print(sql2)
res = cursor.execute(sql2)
print(res) # 1查到成功 0没查到失败
# res=cursor.fetchone()
"""
select * from usr_pwd where username='2222' or 4=4 -- aaa' and password='' 
相当于 : select * from usr_pwd where 10=10; 绕开了账户和密码的判断 -- 代表的是注释;
"""
if res:
print("登录成功")
else:
print("登录失败")

cursor.close()
conn.close()
'''
# (2) 预处理机制
""" 在执行sql语句之前,提前对sql语句中出现的字符进行过滤优化,避免sql注入攻击 """
""" execute( sql , (参数1,参数2,参数3 .... ) ) execute2个参数默认开启预处理机制 """
""" 填写 234234' or 100=100 -- sdfsdfsdfsdf  尝试攻击  """

user = input("请输入您的用户名>>>")
pwd  = input("请输入您的密码>>>")

conn = pymysql.connect(host="127.0.0.1" , user="root" , password="123456",database="db005")
cursor = conn.cursor()
sql = "select * from usr_pwd where username=%s and password=%s"
res = cursor.execute(sql , (user,pwd)  )
print(res)

print(    "登录成功"  if res else "登录失败"    )

cursor.close()
conn.close()

# ### python 操作mysql 数据库 (增删改查)
import pymysql
"""
python 操作mysql增删改时,默认是开启事务的,
必须最后commit提交数据,才能产生变化

提交数据: commit 
默认回滚: rollback

"""

conn = pymysql.connect(host="127.0.0.1",user="root",password="123456",database="db005")
# 默认获取查询结果时是元组,可以设置返回字典;  cursor=pymysql.cursors.DictCursor
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)

# 执行对mysql 的操作

# 1.增
"""
sql = "insert into t1(first_name,last_name,sex,age,money) values(%s,%s,%s,%s,%s)"
# (1) 一次插入一条
res = cursor.execute( sql , ("孙","健",0,15,20000)  )
print(res) # 1
# 获取最后插入这条数据的id号
print(cursor.lastrowid)

# (2) 一次插入多条
res = cursor.executemany(  sql , [  ("安","晓东",0,18,30000) , ("刘","玉波",1,20,50000) ,("张","光旭",0,80,60000) , ("李","是元",0,10,10) , ("高","大奥",1,20,80000)   ]   )
print(res) # 返回插入的条数
# 插入5条数据中的第一条数据的id
print(cursor.lastrowid)
# 获取最后一个数据的id
sql = "select id from t1 order by id desc limit 1"
res = cursor.execute(sql)
print(res)
# 获取结果,返回元组
res = cursor.fetchone()
print(res["id"])
# 默认元组 : (57, '高', '大奥', 1, 20, 80000.0)
# 返回字典 : {'id': 51, 'first_name': '高', 'last_name': '大奥', 'sex': 1, 'age': 20, 'money': 80000.0}
"""

# 2.删
"""
sql = "delete from t1 where id in (%s,%s,%s)"
res = cursor.execute(sql , (3,4,5) )
print(res) # 返回的是3,代表删除了3条

if res:
print("删除成功")
else:
print("删除失败")
"""

# 3.改
"""
sql = "update t1 set first_name = '王' where id = %s"
sql = "update t1 set first_name = '王' where id in (%s,%s,%s,%s)"
res = cursor.execute(sql , (6,7,8,9))
print(res) # 返回的是4,代表修改了4条

if res:
print("修改成功")
else:
print("修改失败")
"""

# 4.查
"""
fetchone  获取一条
fetchmany 获取多条
fetchall  获取所有
"""    

sql = "select * from t1"
res = cursor.execute(sql)
print(res) # 针对于查询语句来说,返回的res是总条数;

# (1) fetchone 获取一条
res = cursor.fetchone()
print(res)
res = cursor.fetchone()
print(res)

# (2) fetchmany 获取多条
res = cursor.fetchmany() # 默认获取的是一条数据,返回列表,里面里面是一组一组的字典;
data = cursor.fetchmany(3)
print(data)
"""
[
{'id': 9, 'first_name': '王', 'last_name': '是元', 'sex': 0, 'age': 10, 'money': 10.0}, 
{'id': 10, 'first_name': '孙', 'last_name': '健', 'sex': 0, 'age': 15, 'money': 20000.0}, 
{'id': 11, 'first_name': '安', 'last_name': '晓东', 'sex': 0, 'age': 18, 'money': 30000.0}
]
"""
for row in data:
first_name = row["first_name"]
last_name = row["last_name"]
sex = row["sex"]
if sex == 0:
sex = "男性"
else:
sex = "女性"
age = row["age"]
money = row["money"]
strvar = "姓:{},名:{},性别:{},年龄:{},收入:{}".format(first_name,last_name,sex,age,money)
print(strvar)

# (3) fetchall 获取所有
# data = cursor.fetchall()
# print(data)

# (4) 自定义搜索查询的位置
print("<==================>")
# 1.相对滚动 relative
"""相对于上一次查询的位置往前移动(负数),或者往后移动(正数)"""
"""
cursor.scroll(-1,mode="relative")
# cursor.scroll(5,mode="relative")
res = cursor.fetchone()
print(res)
"""
# 2.绝对滚动 absolute
"""永远从数据的开头起始位置进行移动,不能向前滚"""
cursor.scroll(0,mode="absolute")
res = cursor.fetchone()
print(res)

conn.commit()
cursor.close()
conn.close()

# ### (1) 导入导出 不要加分号
导出数据库
1.退出mysql
2.选择要导出的默认路径
3.mysqldump -uroot -p db001 > db001.sql

导入数据库
1.登录到mysql之后
2.创建新的数据库
3.source 路径+文件

# ### (2) 配置linux下的编码集
!includedir  /etc/mysql/conf.d/       客户端的修改
# 设置mysql客户端默认字符集
default-character-set=utf8
!includedir  /etc/mysql/mysql.conf.d/ 服务端的修改
# 服务端使用的字符集默认为8比特编码的latin1字符集
character-set-server=utf8

service mysql restart