2019 7.4学习笔记

import pymysql

conn=pymysql.connect(host=‘localhost‘,user=‘root‘,password=‘‘,database=‘pymysql_demo‘)
cursor=conn.cursor()

# select username,age from user where id=1
# select * from user
# select id,username,age,password from user # 等价于上一条
# sql="""
# select username,age from user where id=1
# """
#############  fetchone #############

# sql="""
# select * from user
# """
# cursor.execute(sql)
# while True:
#     result=cursor.fetchone()
#     if result:
#         print(result)
#     else:break
# conn.close()
#############  fetchall #############  fetchmany  后面制定一个参数设置查询到多少数据
sql="""
select * from user
"""
cursor.execute(sql)
results=cursor.fetchall()
for result in results:
    print(result)
conn.close()