Python检查来自用户输入的空值，并且不包括在sql更新中
Python检查来自用户输入的空值，并且不包括在sql更新中
提问于 2018-08-03 08:54:00
在我的函数中，我要求用户输入不同的变量，然后更新数据库。问题是，如果他们没有输入任何东西，有没有一种方法我不能将任何东西推送到DB？当他们没有为var输入值时，DB中的值将被清除。
db_root = '/var/lib/mysql/'
db_to_create = 'students'
db_to_use = 'students'
conn = pymysql.connect(host='localhost', user='root', passwd='dbadmin', cursorclass=pymysql.cursors.DictCursor)
print('Connection successful!!')
def modify_student():
student_id = input("Enter the id of the student record you wish to modify: ")
student_info = input("Is this student personal information you want to modify - y or n: ")
if student_info == 'y':
firstname = input("Enter the first name: ")
lastname = input("Enter the last name: ")
email = input("Enter the email address: ")
address = input("Enter the address: ")
DOB = input("Enter the DOB in YYYY-MM-DD: ")
cur = conn.cursor()
command = "use %s; " %db_to_use
cur.execute(command)
sql = "UPDATE students_info SET firstname = %s, lastname = %s, email = %s, address = %s, DOB = %s WHERE ID = %s;"
cur.execute(sql, [firstname, lastname, email, address, DOB, student_id])
print(cur.execute)
conn.commit()
cur.close()
conn.close()
else:
print("else")
modify_student()
######## SCHEMA ##################
MariaDB [students]> DESCRIBE students_info;
+-----------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+----------------+
| ID | int(11) | NO | PRI | NULL | auto_increment |
| firstname | varchar(255) | YES | | NULL | |
| lastname | varchar(255) | YES | | NULL | |
| email | varchar(255) | YES | | NULL | |
| address | varchar(255) | YES | | NULL | |
| DOB | date | YES | | NULL | |
| english | varchar(255) | YES | | NULL | |
| maths | varchar(255) | YES | | NULL | |
| history | varchar(255) | YES | | NULL | |
| science | varchar(255) | YES | | NULL | |
+-----------+--------------+------+-----+---------+----------------+回答 2
Stack Overflow用户
发布于 2018-08-03 09:21:14
您可以使用以下helper函数：
def mandatory_input(prompt):
while True:
value = input(prompt)
if value:
return value
print("You did not enter the required information.")并用它替换所有被认为是强制性的input提示，因此：
student_id = input("Enter the id of the student record you wish to modify: ")变成：
student_id = mandatory_input("Enter the id of the student record you wish to modify: ")依此类推，因此用户将一直被提示输入值，直到他们输入某些值。
Stack Overflow用户
发布于 2018-08-03 09:24:06
此外，如果您想等待用户完成，然后在用户输入后进行验证：
if all([firstname, lastname, email, ...]):
cur = conn.cursor()
...
else:
print('User missed an input')页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/51663957
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