列表生成式的用法

Posted 2020-11-03 我已不爱凯蒂

import pymysql
def my_db(sql,port=3306,charset=\'utf8\'):
   import pymysql
   host, user, passwd, db = \'118.24.3.40\',\'jxz\',\'123456\',\'jxz\'

   coon = pymysql.connect(user=user,host=host,port=port,passwd=passwd,db=db,charset=charset)
   cur = coon.cursor(cursor=pymysql.cursors.DictCursor) #建立游标,指定cursor类型返回的是字典
   cur.execute(sql)#执行sql
   if sql.strip()[:6].upper()==\'SELECT\':
      # res = cur.fetchall()
      # fileds = []
      # for filed in cur.description:
      #  fileds.append(filed[0])
      fileds = [ filed[0] for filed in cur.description ]  #列表生成式的写法，作用和上面3行代码的意思是一样。其中cur.description返回一个而为元组，查询到所有内容，如图：

       

      print(fileds)   #打印，查看
      res= \'xx\'
   else:
      coon.commit()
      res = \'ok\'
   cur.close()
   coon.close()
   return res
res = my_db(\'select * from users_info limit 10;\')
print(res)

输入结果：