pymysql
# 1.先安装pymysql 模块 pip3 install pymysql
import pymysql
# 相当于mysql的客户端程序
# 前端中获取的用户名和密码
username = input('请输入用户名:')
pwd = input('请输入密码:')
# 建立连接
conn = pymysql.connect(
host = '127.0.0.1',
port = 3306,
db = 'db20',
user = 'root',
password='',
charset ='utf8'
)
# 创建游标
cur = conn.cursor()
# select * from userinfo where name = 'alex' and password = '123';
sql = "select * from userinfo where name = '%s' and password = '%s'" %(username,pwd)
print(sql)
# 执行sql 返回是查询的成功的记录
result = cur.execute(sql) 使用这个可以防止sql注入
print(result)
# 游标关闭 连接关闭
cur.close()
conn.close()
if result:
# 响应 数据 到前端
print('登录成功')
else:
print('登录失败')
sql = "select * from userinfo where name = %(name)s and password = %(password)s"
print(sql)
# sql --
# 执行sql 返回是查询的成功的记录
result = cur.execute(sql,{"name":username,"password":pwd})
print(result)# 字典
# 1.先安装pymysql 模块 pip3 install pymysql
import pymysql
# 相当于mysql的客户端程序
# 建立连接
conn = pymysql.connect(
host = '127.0.0.1',
port = 3306,
db = 'db20',
user = 'root',
password='',
charset ='utf8'
)
# 创建游标
cur = conn.cursor()
# 插入
# select * from userinfo where name = 'alex' and password = '123';
sql = "insert into userinfo(name,password) values (%s,%s)"
# 更改
# sql = "update userinfo set name = %s where id = 3"
# 更改
# sql = "delete from userinfo where id = 3"
# print(sql)
# sql --
# 执行sql 插入数据 删除数据 更改数据 一定记得commit()
# 插入一条数据
# result = cur.execute(sql)
# 插入多条数据
result = cur.executemany(sql,[('alex2','321'),('alex3','678')])
print(result)
# 一定要提交
conn.commit()
# 游标关闭 连接关闭
cur.close()
conn.close()
查询
:
创建游标 查询出来的记录 是字典的形式 cur = conn.cursor(cursor=pymysql.cursors.DictCursor) # select * from userinfo where name = 'alex' and password = '123'; sql = "select * from userinfo" print(sql) # sql -- # 执行sql 返回是查询的成功的记录 result = cur.execute(sql) print(result) # rows = cur.fetchone() # print(rows) # rows = cur.fetchone() # print(rows) # rows = cur.fetchone() # print(rows) # rows = cur.fetchone() # print(rows) # 查询多条数据 # rows = cur.fetchmany(2) # 查询所有的数据 rows = cur.fetchall() print(rows)
elect * from userinfo where name = 'alex' and password = '123'; sql = "select * from userinfo" print(sql) # sql -- # 执行sql 返回是查询的成功的记录 result = cur.execute(sql) print(result) rows = cur.fetchone() print(rows) rows = cur.fetchone() print(rows) cur.scroll(1,mode='absolute') rows = cur.fetchone() print(rows) # rows = cur.fetchone() # print(rows) # rows = cur.fetchone() # print(rows) # rows = cur.fetchone() # print(rows)
只有一页 和下一页
1,记录当前页的最大id或者最小的id
下一页:
select * from user where id > max_id limit 10,
select 8 from user where id< min order by id desc limit 10;
2,页面有页码的情况
select * from user where id in (
select id from (select *from user where id > pre_max_id limit (cu)max_id-pre_max_id)*10 ) as A order by A.id desc limit 10);
select * from (select * from user where id > 1500011 limit 30) as A order by id order by desc;