Python操作mysql数据库

操作步骤：

python读取MySQL的配置文件；
根据读取到的配置文件连接MySQL；
Python连接MySQL后，进行操作，增删改查。

ConfigParser模块

ConfigParser是Python的自带模块，可以读取配置文件。ini是常见的配置文件格式。

配置文件的格式：

[sesion]

host=127.0.0.1

port=3306

user=root

password=123456

db_name=test

代码操作

project：



配置文件：



mysql_db.py

#config=utf8
import os
import configparser as cparser
import pymysql.cursors

#--------读取配置文件-----------
#获取当前脚本的路径
base_dir = os.path.dirname(os.path.dirname(__file__))
base_dir = str(base_dir)
base_dir = base_dir.replace('\\','/')
file_path = base_dir + '/db_conf.ini'
print(file_path)
#读取配置文件
cf = cparser.ConfigParser()
cf.read(file_path)
host = cf.get("mysql_conf",'host')
port = cf.get("mysql_conf",'port')
user = cf.get("mysql_conf",'user')
password = cf.get("mysql_conf",'password')
db_name = cf.get("mysql_conf",'db_name')
print(host,port,user,password,db_name)

#----------python操作MySQL----------
class DB():
#__init__()方法连接mysql数据库
def __init__(self):
try:
self.connection = pymysql.connect(host = host,
user = user,
password = password,
db = db_name,
charset = 'utf8mb4',
cursorclass = pymysql.cursors.DictCursor
)
except pymysql.err.OperationalError as e:
print(e)
print("连接失败")
#建立数据表
def create_table(self):
sql1 = "create table students(" \
"id int not null," \
"name varchar(20) not null," \
"sex varchar(10) not null," \
"tall float," \
"address varchar(255)" \
");"
sql2 = "alter table students add constraint id_pk primary key (id);"
print(sql1)
print(sql2)
with self.connection.cursor() as cursor:
cursor.execute(sql1)
cursor.execute(sql2)
self.connection.commit()
#删除表
def drop_table(self,table_name):
sql3 = "drop table " + table_name + ";"
print(sql3)
with self.connection.cursor() as cursor:
cursor.execute(sql3)
self.connection.commit()
#清空数据表
def clear_table(self,table_name):
sql4 = "truncate table"+" "+table_name + ";"
print(sql4)
with self.connection.cursor() as cursor:
cursor.execute(sql4)
self.connection.commit()
#插入数据（插入的数据封装成字典）
def insert(self,table_name,table_data):
for i in table_data:
#遍历字典获取每一个key值，再获取每个value，把values str()为字符串的形式，
# 因为在sql语句中，值是字符串的形式的。
table_data[i] = "'" + str(table_data[i]) + "'"
#print(table_data[i])
key = ",".join(table_data.keys())      #以逗号分割keys
value = ",".join(table_data.values())  #以逗号分割values
sql = "insert into" + " " + table_name + "(" +key + ")"+"values" + "(" + value + ")" + ";"
print(sql)
with self.connection.cursor() as cursor:
cursor.execute(sql)
self.connection.commit()
#断开数据库连接
def close(self):
self.connection.close()
if __name__ == "__main__":
db = DB()
#db.create_table()
db.clear_table(table_name="students")
table_data = {"id":"1","name":"liyue","sex":"boy"}
db.insert(table_name="students",table_data=table_data)
#db.drop_table(table_name="students")

test_data.py

#coding=utf8
from .mysql_db import DB

#创建测试数据(插入一张数据表)，多张表需要另外封装字典。
datas = [
{"id":"1","name":"liyu","sex":"boy","tall":"190","address":"china"},
{"id":"2","name":"liyue","sex":"boy","tall":"189","address":"china"},
{"id":"3","name":"liudong","sex":"girl","tall":"180","address":"china"},
{"id":"4","name":"liu","sex":"boy","tall":"170","address":"china"},
{"id":"5","name":"liyue","sex":"boy","tall":"160","address":"china"},
{"id":"6","name":"liyue","sex":"boy","tall":"170","address":"china"},
{"id":"7","name":"liyue","sex":"boy","tall":"150","address":"china"},
{"id":"8","name":"liyue","sex":"boy","tall":"180","address":"china"},
{"id":"9","name":"liyue","sex":"boy","tall":"190","address":"china"},
{"id":"10","name":"liyue","sex":"boy","tall":"160","address":"china"},
{"id":"11","name":"liyue","sex":"boy","tall":"180","address":"china"},
{"id":"12","name":"liyue","sex":"boy","tall":"180","address":"china"},
{"id":"13","name":"liyue","sex":"boy","tall":"180","address":"china"},
{"id":"14","name":"liyue","sex":"boy","tall":"180","address":"china"},
{"id":"15","name":"liyue","sex":"boy","tall":"180","address":"china"},
{"id":"16","name":"liyue","sex":"boy","tall":"180","address":"china"},
{"id":"17","name":"liyue","sex":"boy","tall":"180","address":"china"},
{"id":"18","name":"liyue","sex":"boy","tall":"180","address":"china"},
{"id":"19","name":"liyue","sex":"boy","tall":"180","address":"china"},
{"id":"20","name":"liyue","sex":"boy","tall":"180","address":"china"},
{"id": "21", "name": "liyu", "sex": "boy", "tall": "190", "address": "china"},
{"id": "22", "name": "liyue", "sex": "boy", "tall": "189", "address": "china"},
{"id": "23", "name": "liudong", "sex": "girl", "tall": "180", "address": "china"},
{"id": "24", "name": "liu", "sex": "boy", "tall": "170", "address": "china"},
{"id": "25", "name": "liyue", "sex": "boy", "tall": "160", "address": "china"},
{"id": "26", "name": "liyue", "sex": "boy", "tall": "170", "address": "china"},
{"id": "27", "name": "liyue", "sex": "boy", "tall": "150", "address": "china"},
{"id": "28", "name": "liyue", "sex": "boy", "tall": "180", "address": "china"},
{"id": "29", "name": "liyue", "sex": "boy", "tall": "190", "address": "china"},
{"id": "30", "name": "liyue", "sex": "boy", "tall": "160", "address": "china"},
{"id": "31", "name": "liyue", "sex": "boy", "tall": "180", "address": "china"},
{"id": "32", "name": "liyue", "sex": "boy", "tall": "180", "address": "china"},
{"id": "33", "name": "liyue", "sex": "boy", "tall": "180", "address": "china"},
{"id": "34", "name": "liyue", "sex": "boy", "tall": "180", "address": "china"},
{"id": "35", "name": "liyue", "sex": "boy", "tall": "180", "address": "china"},
{"id": "36", "name": "liyue", "sex": "boy", "tall": "180", "address": "china"},
{"id": "37", "name": "liyue", "sex": "boy", "tall": "180", "address": "china"},
{"id": "38", "name": "liyue", "sex": "boy", "tall": "180", "address": "china"},
{"id": "39", "name": "liyue", "sex": "boy", "tall": "180", "address": "china"},
{"id": "40", "name": "liyue", "sex": "boy", "tall": "180", "address": "china"}
]
#出入测试数据
def test_data():
db = DB()
db.clear_table(table_name="students")
for i in datas:
db.insert(table_name="students",table_data=i)
db.close()
if __name__ == "__main__":
test_data()

数据库查询操作：
在上面的类中增加查询的方法：

fetchone()方法获取一个结果集，返回是衣蛾对象，字典形式；

#查询获取数据
def select1(self,what,table_name,column_name,value):
#select * from table;
sql = "select "+what+" from "+table_name + " where " + column_name +" =" +"'"+value+"'" + ";"
print(sql)
with self.connection.cursor() as cursor:
cursor.execute(sql)
result = cursor.fetchone() #fetchone()方法获取一个查询结果集，返回的是一个对象，字典形式，可以通过字典的方法获取key和value
print(result['pic_id'])
self.connection.commit()返回：

127.0.0.1 3306 root 123456 test
select * from test1 where id ='1 ';
12345   #获取的pic_id对应的值

fetchall()方法返回数据表中所有的行数据，返回的是一个列表，列表的元素是一个个字典，一个字典就是行数据；
#查询获取数据
def select1(self,what,table_name,column_name,value):
#select * from table;
sql = "select "+what+" from "+table_name + " where " + column_name +" =" +"'"+value+"'" + ";"
print(sql)
with self.connection.cursor() as cursor:
cursor.execute(sql)
result = cursor.fetchall()#返回一个列表，列表的元素是一个个字典，每一个字典就是一行数据；
print(result)
pic_id = result[0]['pic_id'] #可以通过字典的形式获取每一个字典的key和value值；
print(pic_id)
self.connection.commit()返回：
select * from test1 where id ='1 ';
[{'id': 1, 'type': 'image', 'pic_id': 12345}]
12345