Python《十一》python和mysql交互

1.python要和mysql交互，我们利用pymysql这个库。

下载地址： 
https://github.com/PyMySQL/PyMySQL

安装(注意cd到我们项目的虚拟环境后)：

python -m pip install pymysql

import pymysql.cursors

# 连接数据库
connection = pymysql.connect(host='localhost',
                             user='root',
                             password='root',
                             db='pythondemo',
                             charset='utf8mb4',
                             cursorclass=pymysql.cursors.DictCursor)

try:
    with connection.cursor() as cursor:
        # Read a single record
        sql = "SELECT * From test"
        cursor.execute(sql)
        result = cursor.fetchone()
        print(result) 
finally:
    connection.close()

返回的结果是字典类型，这是因为在连接数据库的时候我们是这样设置的：

cursorclass=pymysql.cursors.DictCursor

元组类型：

cursorclass=pymysql.cursors.Cursor

Cursor对象

主要有4种：

Cursor 默认，查询返回list或者tuple
DictCursor  查询返回dict，包含字段名
SSCursor    效果同Cursor，无缓存游标
SSDictCursor 效果同DictCursor，无缓存游标。

插入一条数据

#插入数据
try:
    with connection.cursor() as cursor:
        sql = "INSERT INTO test(`title`)VALUES (%s)"
        cursor.execute(sql,["今天的新闻"])

    # 手动提交 默认不自动提交
    connection.commit()
finally:
    connection.close()

一次性插入多条数据：（executemany()有别于execute()）

#插入多条数据
try:
    with connection.cursor() as cursor:
        sql = "INSERT INTO test(`title`)VALUES (%s)"
        cursor.executemany(sql, ["多条数据1", "多条数据2"])

    # 手动提交 默认不自动提交
    connection.commit()
finally:
    connection.close()

sql绑定参数

 sql = "INSERT INTO test(`title`)VALUES (%s)"
        cursor.executemany(sql, ["多条数据1", "多条数据2"])

我们用%s占位，执行SQL的时候才传递具体的值。用列表和元组均可（["多条数据1", "多条数据2"]或者（"多条数据1", "多条数据2"））

二，将分析的金融数据入库

1.建表sql:

CREATE TABLE `fund` (
    `code` varchar(50) NOT NULL,
    `name` varchar(255),
    `NAV` decimal(5,4),
    `ACCNAV` decimal(5,4),
    `updated_at` datetime,
    PRIMARY KEY (`code`)
) COMMENT='基金表'

2.准备插入SQL：

INSERT INTO fund(`code`,`name`,`NAV`,`ACCNAV`,`updated_at`)VALUES (%(code)s,%(name)s,%(NAV)s,%(ACCNAV)s,%(updated_at)s)

注意%(code)s这种占位符，要求我们执行这SQL的时候传入的参数必须是字典数据类型。

通配符有：%d(整型)，%s（字符型），%f（浮点型）

MySQL小知识: 
在插入的时候如果有重复的主键，就更新

insert into 表名 xxxx ON duplicate Key  update 表名

3.完整sql

INSERT INTO fund(code,name,NAV,ACCNAV,updated_at)VALUES (%(code)s,%(name)s,%(NAV)s,%(ACCNAV)s,%(updated_at)s)
ON duplicate Key  UPDATE updated_at=%(updated_at)s,NAV=%(NAV)s,ACCNAV=%(ACCNAV)s;

4.全部sql

# #引入包
# from urllib.request import urlopen
#
# response = urlopen("http://fund.eastmoney.com/fund.html")
# html = response.read();
#
# #这个网页编码是gb2312
# #print(html.decode("gb2312"))
#
# #把html内容保存到一个文件
# with open("1.txt","wb") as f:
#     f.write(html.decode("gb2312").encode("utf8"))
#     f.close()
import pymysql.cursors
from bs4 import BeautifulSoup
from datetime import datetime
updated_at = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
with open("1.txt", "rb") as f:
    html = f.read().decode("utf8")
    f.close()

# 分析html内容
soup = BeautifulSoup(html,"html.parser")

# 取出网页title
#print(soup.title) #

# 基金编码
codes = soup.find("table",id="oTable").tbody.find_all("td","bzdm")

result = () # 初始化一个元组
for code in codes:
    result += ({
                   "code": code.get_text(),
                   "name": code.next_sibling.find("a").get_text(),
                   "NAV": code.next_sibling.next_sibling.get_text(),
                   "ACCNAV": code.next_sibling.next_sibling.next_sibling.get_text(),
                   "updated_at": updated_at
               },)


# 连接数据库
connection = pymysql.connect(host='localhost',
                             user='root',
                             password='root',
                             db='pythondemo',
                             charset='utf8mb4',
                             cursorclass=pymysql.cursors.Cursor)
try:
    with connection.cursor() as cursor:

        sql = """INSERT INTO fund(`code`,`name`,`NAV`,`ACCNAV`,`updated_at`)VALUES (%(code)s,%(name)s,%(NAV)s,%(ACCNAV)s,%(updated_at)s)"""

        cursor.executemany(sql,result)

    # 手动提交 默认不自动提交
    connection.commit()
finally:
    connection.close()