如何使用Python在 SQLite 中读取图像？

本文向我们展示了如何使用Python sqlite3 模块读取或检索以 BLOB 数据类型形式存储在 SQLite 表中的图像。首先，我们需要使用Python脚本读取存储在 BLOB 格式的 SQLite 表中的图像，然后将文件写回硬盘驱动器上的任何位置，以便您可以以适当的格式查看和读取它。

使用的 SQLite 数据库：

这是我们的 sqlite3 数据库。

执行：

在这个例子中，我们正在读取学生姓名和学生图像，它们存储在以 BLOB 形式存储的 SQLite 表中。要使用Python从 SQLite 表中读取 BLOB 数据，您需要执行以下步骤：-

1.使用Python代码设置与SQLite数据库的连接

con = sqlite3.connect('SQLite_Retrieving_data.db')
print("Connected Successfully")

2. 我们需要定义一个 SELECT 查询来从表中获取 BLOB 列。

query = "SELECT * FROM "

3. 使用cursor.execute()在Python执行 SELECT 查询。

cursor = con.cursor()
cursor.execute(query)

4. 使用cursor.fetchall()检索并遍历结果集中的所有行。

records = cursor.fetchall()
    for row in records:
        name = row[0]
        print("Student Name = ", name)

5. 创建一个函数，将BLOB数据转换为正确的格式，并以人类可读的格式保存。

def convert_data(data, file_name):
    # Convert binary format to images or files data
    with open(file_name, 'wb') as file:
        file.write(data)

6.关闭游标连接和MySQL数据库。

if con:
     con.close()
     print("SQLite connection is closed")

下面是实现。

Python3

import sqlite3
from PIL import Image
 
# Function for Convert Binary
# Data to Human Readable Format
def convert_data(data, file_name):
     
    # Convert binary format to
    # images or files data
    with open(file_name, 'wb') as file:
        file.write(data)
    img = Image.open(file_name)
    print(img)
 
try:
       
    # Using connect method for establishing
    # a connection
    con = sqlite3.connect('SQLite_Retrieving_data.db')
    cursor = con.cursor()
    print("Connected Successfully")
 
    # Search from table query
    query = "SELECT * FROM Student"
 
    # using cursor object executing our query
    cursor.execute(query)
     
    # fectching all records from cursor object
    records = cursor.fetchall()
     
    # using for loop retrieving one by one
    # rows or data
    for row in records:
           
        # storing row[0] in name variable
        name = row[0]
         
        # printing name variable
        print("Student Name = ", name)
         
        # storing image (currently in binary format)
        image = row[1]
         
        # calling above convert_data() for converting
        # binary data to human readable
        convert_data(image, "D:\Internship Tasks\GFG\sqlite\\" + name + ".png")
        print("Yeah!! We have successfully retrieved values from database")
 
    # If we don't have any records in our database,
    # then print this
    if len(records) == 0:
        print("Sorry! Please Insert some data before reading from the database.")
 
# print exception if found any during program
# is running
except sqlite3.Error as error:
    print(format(error))
 
# using finally, closing the connection
# (con) object
finally:
    if con:
        con.close()
        print("SQLite connection is closed")

输出：