（使用python连接mysql）mysql-connector-python、pymysql、SQLite3

一、mysql-connector-python

1、安装

pip 安装 mysql-connector-python

2、代码

# 导入API
import mysql.connector 
# 创建数据库
def create_db_sampledb():
# config为数据库的配置信息
    config_root = {
        "host":"localhost",
        "user":"root",
        "password":"1234"
    } # 创建root用户的连接配置
    sql = "Create Database IF Not Exists sampledb CHARSET=utf8 COLLATE=utf8_bin"
    try:
        conn = mysql.connector.connect(**config_root) #创建连接
        cursor = conn.cursor() #设置游标
        cursor.execute(sql) #执行sql语言
        conn.commit() # 上传
    finally:
        conn.close() # 关闭连接
# 设置配置信息，模仿用户配置的信息
mysql_config_sampledb = {
    "host":"127.0.0.1",
    "database":"sampledb",
    "user":"root",
    "password":"1234"
}
# 创建表
def create_table_sampletb():
#     如果该表不存在，创建该表
    sql = (
        "Create Table If Not Exists sampletb("
        "DateTime DateTime Primary key,"
        "open float(32),"
        "high float(32),"
        "low float(32),"
        "close float(32))"
    )
    try:
        conn = mysql.connector.connect(**mysql_config_sampledb)
        cursor = conn.cursor()
        cursor.execute(sql)
        conn.commit()
    finally:
        conn.close()
# 如果存在删除该表
def drop_table_sampletb():
    sql = "DROP TABLE IF EXISTS sampletb"
    try:
        conn = mysql.connector.connect(**mysql_config_sampledb)
        cursor = conn.cursor()
        cursor.execute(sql)
        conn.commit()
    finally:
        conn.close()

#插入数据
import pandas as pd
def insert_into_sampletb():
    df = pd.read_csv("523-628IF00.csv")
    df = df.where(~pd.isnull(df),other=None) # ~表示 非，即保存不是缺失值的数
    sql = (
        "INSERT INTO sampletb"
        "(DateTime,open,high,low,close)"
        "VALUES (%s,%s,%s,%s,%s)"
    )
    try:
        conn = mysql.connector.connect(**mysql_config_sampledb)
        cursor = conn.cursor()
#         cursor.executemany(sql,multiple_data) # 插入多条记录
#         cursor.execut(sql,data) # 插入单条纪录，其中data记录值
        for row in df.iterrows():
            li = row[1].values
            cursor.execute(sql,tuple(li)) # 此处为插入单条数据
        
        conn.commit()
    finally:
        conn.close()
# 查询数据
select_sampletb = "SELECT * FROM sampletb LIMIT 100" # 查询表列名
select_sampletb_columns = "SHOW columns FROM sampletb" #查看数据行数
def select_from_sample(config,sql):
    '''
    查询语句，输入数据库的连接信息(字典)以及查询语句，
    打印查询条数，并返回查询的结果
    '''
    try:
        conn = mysql.connector.connect(**config)
        cursor = conn.cursor()
        cursor.execute(sql)
        result = cursor.fetchall()
    finally:
        conn.close()
    return result
result = select_from_sample(mysql_config_sampledb,select_sampletb) # result为关于查询结果的一个list
# 通过查询函数查询列名
select_from_sample(mysql_config_sampledb,select_sampletb_columns)

二、使用pymysql连接mysql

1、安装

pip install pymysql

2、代码

# 导入API
import pymysql
# 创建数据库
def create_datebase_sampledb2():
    config_root = {
        "host":"localhost",
        "user":"root",
        "password":"1234"
    }
    sql = "Create Database If Not Exists sampleddb2 CHARSET=utf8MB4 COLLATE=utf8mb4_bin"
    conn = pymysql.connect(**config_root) # 打开数据库连接
    try:
        with conn.cursor() as cursor: # 使用cursor()方法获取语法
            cursor.execute(sql) # 执行SQL
            conn.commit() #提交
    finally:
        conn.close()
# 设置配置信息
pymysql_config_sampledb2={
    "host":"127.0.0.1",
    "database":"sampleddb2",
    "user":"root",
    "password":"1234"
}
# 创建表
def create_table_sampletb2():
    '''
    如果该表不存在，创建该表
    '''
    sql = (
        "Create Table If Not Exists sampletb2("
        "DateTime DateTime Primary key,"
        "open float(32),"
        "high float(32),"
        "low float(32),"
        "close float(32))"
    )
    conn = pymysql.connect(**pymysql_config_sampledb2)# 打开连接
    try:
        with conn.cursor() as cursor:
            cursor.execute(sql)
            conn.commit()
    finally:
        conn.close()
# 删除表
def drop_table_sampletb2():
    '''
    如果该表存在，删除该表
    '''
    sql = "DROP TABLE IF EXISTS sampletb2"
    conn = pymysql.connect(**pymysql_config_sampledb2)
    try:
        with conn.cursor() as cursor:
            cursor.execute(sql)
            conn.commit()
    finally:
        conn.close()
# 插入数据
import pandas as pd
def insert_into_sampletb2():
    df = pd.read_csv("523-628IF00.csv")
    df = df.where(~pd.isnull(df),other=None) # ~表示 非，即保存不是缺失值的数
    sql = (
        "INSERT INTO sampletb"
        "(DateTime,open,high,low,close)"
        "VALUES (%s,%s,%s,%s,%s)"
    )
    conn = pymysql.connect(**pymysql_config_sampledb2)
    try:
        with conn.cursor() as cursor:
#         cursor.executemany(sql,multiple_data) # 插入多条记录
#         cursor.execut(sql,data) # 插入单条纪录，其中data记录值
            for row in df.iterrows():
                li = row[1].values
                cursor.execute(sql,tuple(li)) # 此处为插入单条数据
            conn.commit()
    finally:
        conn.close()

其他相关方法和mysql-connector-python中的一样，不再一一重复。

三、SQLite3

SQLite3 和上面的两种方法不一样，上面的两种方法是通过API连接mysql数据库，但是SQLite3是python自带的一个便捷式数据库，而不是去连接，它本身就是一个小型的mysql。
执行创建语句后，会在本地生成一个.db 文件

#导入入模块
import sqlite3
# 设置一个路径作为数据库的保存路径
sqlite3_path="sqlite_sample.db"
# 创建一个数据库并创建一个表
def create_sqlite_sampletb(db_path):
    sql = (
        "Create Table If Not Exists sampletb("
        "DateTime DateTime Primary key,"
        "open float(32),"
        "high float(32),"
        "low float(32),"
        "close float(32))"
    )
    with sqlite3.connect(db_path) as conn:
        cursor = conn.cursor()
        cursor.execute(sql)
        conn.commit()
create_sqlite_sampletb(sqlite3_path)

其他实现数据库的方法，即变换sql语句即可。