Question

在python中写了一个片段，它从数据库中提取数据并将它们显示在python shell上。但是我犯了一些愚蠢的错误，因为我只得到一个日期而不是一个范围内的日期。我的代码如下：

# open a database connection
connection = MySQLdb.connect ()

# prepare a cursor object using cursor() method
cursor = connection.cursor ()

# execute the SQL query using execute() method.
cursor.execute ()

data = cursor.fetchall()
ddt =  sorted(set(data))

def dte():
  for row in ddt:
   date = (' '.join(map(str,row)))
  return date

print dte()

这是我得到的输出：2017-11-09 但相反，我应该在一个范围内获得多个日期，例如：2017-06-17,2017-06-18等等。

Answer 1

你只是在每个日期无所事事地循环，最后，你将返回最后一个。

# open a database connection
connection = MySQLdb.connect ()

# prepare a cursor object using cursor() method
cursor = connection.cursor ()

# execute the SQL query using execute() method.
cursor.execute ()

data = cursor.fetchall()
ddt =  sorted(set(data))

def dte():
    dates = [] #Here you need to store the dates in a list or something
    for row in ddt:
        dates.append(' '.join(map(str,row))) #Then append them to the list
    return(dates) #Finally return them EDITED

for i in dte(ddt):
    print(i)

还有一件事，使用ddt作为参数。这样可以避免范围问题。

像：

def dte(data):
          dates = [] #Here you need to store the dates in a list or something
          for row in data:
           dates.append(' '.join(map(str,row))) #Then append them to the list
          return(dates) #Finally return them

for i in dte(ddt):
     print(i)

Answer 2

return内的函数本身不要print date而是for。

# open a database connection 
connection = MySQLdb.connect () 

# prepare a cursor object using cursor() method 
cursor = connection.cursor () 

# execute the SQL query using execute() method. 
cursor.execute () 

data = cursor.fetchall() 

ddt = sorted(set(data)) 

def dte(): 
    for row in ddt: 
        date = (' '.join(map(str,row))) 
        print(date)      
dte()

Python中的日期范围错误

2 个答案: