如何在python中单行编写if和else

Question

可能重复:
Python中的三元条件运算符

我正在研究python并尝试将数据保存到数据库中假设我有以下代码

conn = mdb.connect(user='root', passwd='redhat', db='Data', host='localhost', charset="utf8")

ex_li = ['stri_one','stri_two','stri_three','stri_four']

if ex_li[0] != '':
    campaignID = ex_li[0]
else:
    campaignID = ''

if ex_li[1] != '':
    keywordID = ex_li[1]
else:
    keywordID = ''
.........
.......

try:
    cursor = conn.cursor()
    query = "insert into PerformaceReport(campaignID, keywordID, keyword, avgPosition,cost)"
    query += "VALUES (%s, '%s', '%s', '%s')" %(campaignID, keywordID, keyword, avgPosition,cost)
    cursor.execute( query )
    conn.commit()
except Exception as e:
    print e,"!!!! Exception happend!!!!"

在上面的代码中,如果它们不等于空字符串,我将从列表中获取字符串,因为在切片期间如果没有字符串则会显示list index out of range错误.

那么有没有办法在一行中编写这些if和else语句并提交为值直接查询如下所示(仅作为一个想法)

        query += "VALUES (%s, '%s', '%s', '%s')" %(if ex_li[0] != '': campaignID = ex_li[0]  else: campaignID = '' ............)

Answer 1

expression_if_true if condition else expression_if_false

所以试试吧

campaignID = main_res[0] if ex_li[0] != '' else ''