Python从用户输入中检查NULL值，并且不包含在sql更新中

Question

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，如果他们不输入任何内容，有没有办法我不能将任何内容推送到数据库？当他们不输入var的值时，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")

Answer 1

您可以使用以下帮助器功能：

def mandatory_input(prompt):

    while True:

        value = input(prompt)

        if value:

            return value

        print("You did not enter the required information.")

并input用它替换所有被认为是强制性的提示，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，以便在用户输入内容之前一直提示用户输入值。