pymysql 模块

一、查询语句

pymsql.cursors的应用

https://blog.csdn.net/tcy23456/article/details/86665211

# 使用pymysql，设计登录
import pymysql
user_name = input('username:')
user_password = input('password:')
conn = pymysql.connect(host='localhost', user='root', password='@WSX3edc', database='db2')  # 连接数据库
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)     # 设置游标卡尺和fetc的格式，以字典的形式返回结果
sql = "select * from userinfo where username =%s and password = %s"     # sql语句，注意在此次不能用格式化，——在sql语句是注释
cursor.execute(sql, [user_name, user_password])     # list tuple dict
ret = cursor.fetchone()     # 取一个值
# print(ret)
cursor.close()  # 关闭游标卡尺
conn.close()    # 关闭连接
if ret:
    print('登录成功!')
else:
    print('登录失败')

import pymysql
conn = pymysql.connect(host='localhost', user='root', password='@WSX3edc', database='db2')  # 连接数据库
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)     # 设置游标卡尺和fetc的格式
sql = "select * from userinfo limit 3"     # sql语句，分页
cursor.execute(sql)     # list tuple dict
ret = cursor.fetchall()     # 取所有值
print(ret)
cursor.close()  # 关闭游标卡尺
conn.close()    # 关闭连接

import pymysql
conn = pymysql.connect(host='localhost', user='root', password='@WSX3edc', database='db2')  # 连接数据库
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)     # 设置游标卡尺和fetc的格式
sql = "select * from userinfo limit 3"     # sql语句，分页

cursor.execute(sql)     # list tuple dict
cursor.scroll(1, mode='absolute')    # 光标到1,默认的模式是相对
ret = cursor.fetchall()     # 取所有值
print(ret)
cursor.close()  # 关闭游标卡尺
conn.close()    # 关闭连接

 模糊查询

"select id from tp_region where title like '%{}%' ".format(cityname)

二、插入语句

# 插入一条数据
import pymysql
conn = pymysql.connect(host='localhost', user='root', password='@WSX3edc', database='db2')
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
sql = "insert into userinfo(username, password) values(%s,%s) "
cursor.execute(sql, ['joker', '1234'])
conn.commit()   # 提交
cursor.close()
conn.close()

import pymysql
conn = pymysql.connect(host='localhost', user='root', password='@WSX3edc', database='db2')
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
sql = "insert into userinfo(username, password) values(%s, %s)"
ret = cursor.executemany(sql, [('peter', '123'), ('talk', '234')])  # 连续添加多个数据，ret 为受影响的行数
conn.commit()
print(ret)
cursor.close()
conn.close()

# 获取自增值
import pymysql
conn = pymysql.connect(host='localhost', user='root', password='@WSX3edc', database='db2')
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
sql = "insert into userinfo(username, password) values(%s, %s)"
ret = cursor.execute(sql, ['talk', '234'])  # 连续添加多个数据，ret 为受影响的行数
conn.commit()
print(cursor.lastrowid)     # 获取自增值
print(ret)
cursor.close()
conn.close()

 三、改

import pymysql
conn = pymysql.connect(host='localhost', user='root', password='@WSX3edc', database='db3', charset='utf8')
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
sql = 'update test4 set age =%s where name=%s'
cursor.execute(sql, [20, 'tom'])
conn.commit()
sql1 = 'select * from test4'
cursor.execute(sql1)
ret = cursor.fetchall()
print(ret)
cursor.close()
conn.close()

四、删

import pymysql
conn = pymysql.connect(host='localhost', user='root', password='@WSX3edc', database='db3', charset='utf8')
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
sql = 'delete from test4 where name = %s'
cursor.execute(sql, 'tom')
conn.commit()
sql1 = 'select * from test4'
cursor.execute(sql1)
ret = cursor.fetchall()
print(ret)
cursor.close()
conn.close()