爬虫文件存储-1：mysql

1.连接并创建数据库

import pymysql

db = pymysql.connect(host='localhost', user='root', password='root', port=3306)

cursor = db.cursor()

cursor.execute('SELECT VERSION()')

data = cursor.fetchone()

print('Database version:', data)

cursor.execute("CREATE DATABASE spiders DEFAULT CHARACTER SET utf8")

db.close()

执行结果：

Database version: ('5.7.23',)

结果是创建一个名为spiders的数据库

2.创建数据表

注意：这次连接数据库时需要指定创建数据表所在的数据库，也就是db参数的值

import pymysql

db = pymysql.connect(host='localhost', user='root', password='root', port=3306, db='spiders')

cursor = db.cursor()

sql = 'CREATE TABLE IF NOT EXISTS students (id VARCHAR(255) NOT NULL, name VARCHAR(255) NOT NULL, age INT NOT NULL, PRIMARY KEY (id))'

cursor.execute(sql)

db.close()

3.插入一条数据

import pymysql

db = pymysql.connect(host='localhost', user='root', password='root', port=3306, db='spiders')

cursor = db.cursor()

id = ''

user = 'Bob'

age = 20

sql = 'INSERT INTO students(id, name, age) values(%s, %s, %s)'

try:

    cursor.execute(sql, (id, user, age))

    db.commit()

except:

    db.rollback()

db.close()

通用写法：

这样一来，若是写入更多值的话直接给data字典增加数据就行了，就不用其他sql语句了，推荐使用

import pymysql

db = pymysql.connect(host='localhost', user='root', password='root', port=3306, db='spiders')

cursor = db.cursor()

table = 'students'

data = {

    'id': '',

    'name': 'Bob11',

    'age': 200

}

keys = ', '.join(data.keys())

values = ', '.join(['%s'] * len(data))

sql = 'INSERT INTO {table} ({keys}) VALUES ({values})'.format(table=table, keys=keys, values=values)

try:

    if cursor.execute(sql, tuple(data.values())):

        print('Successful')

        db.commit()

except:

    print('Failed')

    db.rollback()

db.close()

4.更新数据

import pymysql

db = pymysql.connect(host='localhost', user='root', password='root', port=3306, db='spiders')

cursor = db.cursor()

sql = 'UPDATE students SET age = %s WHERE name = %s'

try:

   cursor.execute(sql, (25, 'Bob'))

   db.commit()

except:

   db.rollback()

db.close()

通用写法：

根据主键进行判断，若主键存在则更新，若不存在则插入，推荐使用

import pymysql

db = pymysql.connect(host='localhost', user='root', password='root', port=3306, db='spiders')

cursor = db.cursor()

table = 'students'

data = {

    'id': '',

    'name': 'Bob',

    'age': 21

}

keys = ', '.join(data.keys())

values = ', '.join(['%s'] * len(data))

sql = 'INSERT INTO {table}({keys}) VALUES ({values}) ON DUPLICATE KEY UPDATE'.format(table=table, keys=keys,

                                                                                     values=values)

update = ','.join([" {key} = %s".format(key=key) for key in data])

sql += update

try:

    if cursor.execute(sql, tuple(data.values()) * 2):

        print('Successful')

        db.commit()

except:

    print('Failed')

    db.rollback()

db.close()

5.删除数据

import pymysql

db = pymysql.connect(host='localhost', user='root', password='root', port=3306, db='spiders')

cursor = db.cursor()

table = 'students'

condition = 'age > 20'

sql = 'DELETE FROM  {table} WHERE {condition}'.format(table=table, condition=condition)

try:

    cursor.execute(sql)

    db.commit()

except:

    db.rollback()

db.close()

6.查询数据

import pymysql

db = pymysql.connect(host='localhost', user='root', password='root', port=3306, db='spiders')

cursor = db.cursor()

sql = 'SELECT * FROM students WHERE age >= 20'

try:

    cursor.execute(sql)

    print('Count:', cursor.rowcount)

    row = cursor.fetchone()

    while row:

        print('Row:', row)

        row = cursor.fetchone()

except:

    print('Error')

巴特西

爬虫文件存储-1：mysql

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