为什么数据库的用户名和PIN部分未被识别？

Question

# PHASE 2 (With Database) SQLite 3 

# Define Connection and Cursor 
connection = sqlite3.connect('Bank_Users.db')
cursor = connection.cursor()

# Create Users Table 
command1 = """ CREATE TABLE IF NOT EXISTS 
bank(pin INTEGER PRIMARY KEY , username text )"""
cursor.execute(command1)

# Add to Users/Bank
cursor.execute("INSERT INTO bank VALUES (7620, 'Kailas Kurup')")
cursor.execute("INSERT INTO bank VALUES (4638, 'Bethany Watkins')")
cursor.execute("INSERT INTO bank VALUES (3482, 'John Hammond')")
cursor.execute("INSERT INTO bank VALUES (3493, 'Melissa Rodriguez')")
cursor.execute("INSERT INTO bank VALUES (9891, 'Kevin Le')")

# Get Results / Querying Database
cursor.execute("SELECT username, pin FROM bank")
results = cursor.fetchall()
print(results)

# Check Database User Info  
def read_from_db():
    for row in cursor.fetchall():
        if username in row: 
            if pin in row: 
                print ("Success")
        else: 
            print("Invalid Pin")

**我正在尝试根据输入的用户名和PIN检查数据库。例如，如果输入了7620和Kailas Kurup以外的用户名和PIN，它将返回“无效”。但是我的代码无法识别，并且“用户名”和“ PIN”下有弯曲的线条。为什么会发生这种情况以及如何解决？我正在使用Visual Studio代码（VSCODE）。