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python - 显示消息框数据已存在

问题描述

我想把 ErrorMessageBox 放在这段代码上。就像它表明“数据已经存在”一样。

这是保存到数据库的代码块：

if (t1.get()==""  or t2.get()=="" or t3.get()=="" or t4.get()==""):
        messagebox.showinfo("Result","Please Complete the Provided Details!")

这里连接到数据库和插入

    else:
        databases = mysql.connector.connect(
        host ="localhost",
        user = "userdata",
        password = "",
        database = "facerecog"
        )

        cursors = databases.cursor()
        cursors.execute("SELECT * from record")
        result = cursors.fetchall()

这是将数据插入数据库的代码

        id= t4.get()
        id = int(id)+1
        id
        sql = "INSERT INTO record(ids, names,course_year,positions) values(%s ,%s ,%s , %s)"
        val = (id, t1.get(), t2.get(), t3.get())
        cursors.execute(sql,val)
        databases.commit()

如果数据已经存在，我想放置 ErrorMessageBox 。

在这段代码中拍照。此代码连接到保存数据库。

        face_classifier = cv2.CascadeClassifier("haarcascade_frontalface_default.xml")
        def face_cropped(img):
            gray = cv2.cvtColor(img,cv2.COLOR_BGR2RGB)
            faces = face_classifier.detectMultiScale(gray, 1.3, 5)
            # scaling factor = 1.3
            # minimum neighbor = 5
            if faces is ():
                return None
            for (x,y,w,h) in faces:
                    cropped_face = img[y:y+h, x:x+w]
            return cropped_face

        cap = cv2.VideoCapture(0)
        img_id = 0

        while True:
            ret, frame = cap.read()
            if face_cropped(frame) is not None:
                img_id+=1

                face = cv2.resize(face_cropped(frame), (200,200))
                face = cv2.cvtColor(face,cv2.COLOR_BGR2GRAY)

                file_name_path = "img/"+str (t1.get())+"." +str(id)+"."+str(img_id)+".jpg"


                cv2.imwrite(file_name_path, face)

                cv2.putText(face, str(img_id), (50,50), cv2.FONT_HERSHEY_COMPLEX, 1, (0,255,0), 2)

                cv2.imshow("Cropped face", face)

            if cv2.waitKey(1)==1 or int(img_id)==50:

                break

        cap.release()
        cv2.destroyAllWindows()

        messagebox.showinfo("Result","Saved Completed!")

标签： pythontkinterphpmyadminlocalhost

解决方案

这是适合您的方法。

您可以尝试插入数据库，如果数据已经存在，它将引发异常，您可以使用所需的消息处理该异常。

import mysql.connector
from mysql.connector import IntegrityError

cnx = mysql.connector.connect(user='root', database='test', host='localhost', password='mypass')
cursor = cnx.cursor()

#This insert is only for duplication purposes since your id must be auto_incremental
query = ("INSERT INTO students (id, name) values (3, 'andy')")

try:
    cursor.execute(query)
    cnx.commit()
except IntegrityError:
    print("Data already exists!")
finally:
    cursor.close()
    cnx.close()

@furas 建议的第二种方法，如果您的结果不为空，则首先执行选择以检索您的数据，然后您的数据存在。

import mysql.connector

cnx = mysql.connector.connect(user='root', database='test', host='localhost', password='mypass')
cursor = cnx.cursor()

name = 'andy'
query = f"SELECT * FROM students WHERE name = '{name}'"

try:
    cursor.execute(query)
    res = cursor.fetchall()
    if res is not None:
        print(f"Data already exists: {res}")
    else:
        #Execute your insertion
        pass
finally:
    cursor.close()
    cnx.close()

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