Python + MariaDB跳过else语句

1sbrub3j  于 2022-11-08  发布在  Python
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我正在尝试使用Python来记录为显示包裹而扫描的条形码。我希望最终使用OpenCV作为输入,但不想限制每个包裹的扫描次数,因此我希望测试一下包裹是否已经在MariaDB中标记为已发货。
输入工作(从手持扫描仪现在),它正在查找数据库,看看条形码是否已被扫描之前罚款,但当它谈到一个没有,它似乎跳过了其他语句。我已经盯着这个代码多年了!任何帮助感谢。谢谢

import mariadb
import sys

from datetime import datetime
now  = datetime.now()
dt_string = now.strftime("%d/%m/%Y %H:%M:%S")
print("date and time =", dt_string)

conn = mariadb.connect(
    user="root",
    password="password",
    host="localhost",
    database="pythontest")
cur = conn.cursor()

while True:
    barcode=input("--->  ")
    if barcode.startswith("%"):
        courier = ("DPD")
    elif barcode.startswith("JD"):
        courier = ("Royal Mail")
    else:
        courier = ("Unknown Courier")
        print("Unknown Courier")
    cur.execute("SELECT trackingNumber,status,shipTime,courier FROM opencvdb WHERE trackingNumber=?", (barcode,))
    for trackingNumber, status, shipTime, courier in cur:
        if trackingNumber in barcode:
            print(f"Already Shipped at {shipTime} with {courier} - Tracking Number: {barcode}")
        else:
            try:
                print("Shipping Now")
                cur.execute("INSERT INTO opencvdb (trackingNumber,status,shipTime,courier) VALUES (?, ?, ?, ?)", (barcode, "Done", dt_string,courier))
            except mariadb.Error as e:
                print(f"Error: {e}")

            conn.commit()
            print(f"Last Inserted ID: {cur.lastrowid}")

conn.close()
rggaifut

rggaifut1#

如果此查询未返回任何结果(因为没有匹配的记录)
cur.execute("SELECT trackingNumber,status,shipTime,courier FROM opencvdb WHERE trackingNumber=?", (barcode,))
那么这个for语句就没有要循环的内容
for trackingNumber, status, shipTime, courier in cur:
并且永远不会执行此语句
if trackingNumber in barcode:

更新:我认为这可能是您想要做的:

cur.execute("select...")
found = False
for (trackingNumber, status....) in cur.fetchall():
    found = True
    print("Already shipped...")

if not found:
    cur.execute("insert into....")
    conn.commit()

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