1.列表推导式
- 列表推导式
a = [i for i in range(1, 10)]
print(a)
a = [i for i in range(1, 10) if i % 2 == 0]
print(a)
a = [(i, j) for i in range(1, 3) for j in range(1, 3)]
print(a)
a = [(i, j, k) for i in range(1, 3) for j in range(1, 3) for k in range(1, 3)]
print(a)
打印结果如下：
[1, 2, 3, 4, 5, 6, 7, 8, 9]
[2, 4, 6, 8]
[(1, 1), (1, 2), (2, 1), (2, 2)]
[(1, 1, 1), (1, 1, 2), (1, 2, 1), (1, 2, 2), (2, 1, 1), (2, 1, 2), (2, 2, 1), (2, 2, 2)]
-
集合类型
image.png
注意：使用set ，可以快速的完成对list中的元素去重复功能
2.连接数据库
# 首先得导入pymysql
import pymysql as pm
# 创建连接
coon = pm.connect("localhost", "root", "123456", "vhr")
# 增删改查
course = coon.cursor()
course.execute("SELECT * FROM role")
role = course.fetchone()
print(role)
roles = course.fetchall()
print(roles)
# 关闭数据库连接
coon.close()
一个数据库连接工具：mysql_util.py
import pymysql
class MysqlHelper(object):
config = {"host": "localhost", "user": "root", "password": "123456", "db": "db_spring", "charset": "utf8"}
def __init__(self):
self.connection = None
self.cursor = None
def getOne(self, sql, *args):
try:
self.connection = pymysql.connect(**MysqlHelper.config)
self.cursor = self.connection.cursor()
self.cursor.execute(sql, args)
return self.cursor.fetchone()
except Exception as ex:
print(ex, ex)
finally:
self.close()
def getList(self, sql, *args):
try:
self.connection = pymysql.connect(**MysqlHelper.config)
self.cursor = self.connection.cursor()
self.cursor.execute(sql, args)
return self.cursor.fetchall()
except Exception as ex:
print(ex, ex)
finally:
self.close()
def executeDML(self, sql, *args):
try:
self.connection = pymysql.connect(**MysqlHelper.config)
self.cursor = self.connection.cursor()
self.cursor.execute(sql, args)
new_id = self.connection.insert_id()
self.connection.commit()
return new_id
except Exception as ex:
print(ex, ex)
finally:
self.close()
def close(self):
if self.cursor:
self.cursor.close()
if self.connection:
self.connection.close()
if __name__ == "__main__":
helper = MysqlHelper()
print(
helper.executeDML("INSERT INTO user(username,password,enabled,locked) VALUES (%s,%s,%s,%s)", "王朝", "123456", 1,
1))
