删除SQL数据库中不存在的图像

Question

I have a table of products in my sql database. Each product has an image and 4 thumbnails. These just store the filename of an image on the hard drive. The problem I have is that over time I have deleted thousands of products but the images still remain on the hard drive.

Now I need to build a script (in c# .net) to remove any orphaned images. I assume the only way is to get a list of products into memory and loop though all the images in the directory to cross reference and remove if they don't exist.

Has anyone come across this before and can you give me any advice?

Answer 1

A quicker way would be to write a procedure that moves all the images that are referenced to a new folder on the same hard drive. Then once you've verified you've got them all delete (or rename if you're feeling nervous) the old folder and finally rename the new one back to the original name.

You should backup the original folder first, just in case.

Answer 2

An idea comes to mind: Can you somehow flag the images that you DO need? In the most basic way you could rename them temporarily to lets say used_xxx.jpg

Then cursively loop your folders and delete all the images that dont have the used_ prefix. After that you rename back the still existing images to their original names.

Edit: This way you wouldn't have to copy anything. And you have a visual reference so you can see what you're doing.

Answer 3

That really is the only way you would do it. I would suggest first iterating through the product images in the database and build a List<string> with their names and paths, then use the Directory object to pull a list of all images, recursively if necessary, in your images directory.

Then go through each file in the returned listing and compare it with your List<string> . If it doesn't exist in the list, delete it off the filesystem.

Remember to back up, just in case!

Answer 4

您似乎已经回答了自己的问题...而不是遍历目录中的所有图像，您可以迭代数据库中的所有产品，并且每个产品将图像复制到新文件夹，但它几乎相同事情。

Answer 5

If you're familiar with PowerShell at all, this seems like something which it would be good at doing. Here's a way to do it in T-SQL if your SQL server happens to be MS SQL Server and you have rights to run xp_cmdshell. I just wrote this out, so it doesn't have error checking, etc.

DECLARE
    @image_files TABLE (file_path VARCHAR(MAX))

DECLARE
    @file_path VARCHAR(MAX),
    @cmd VARCHAR(MAX)

INSERT INTO @image_files (file_path)
EXEC xp_cmdshell 'dir *.jpg /b /s /x'
-- Change the extension if you use GIF, etc.

DECLARE file_cursor CURSOR FOR
    SELECT
        file_path
    FROM
        @image_files
    WHERE
        file_path NOT IN
        (
            SELECT file_path
            FROM
                My_Files
        )

OPEN file_cursor

FETCH NEXT FROM file_cursor INTO @file_path

WHILE (@@FETCH_STATUS = 0)
BEGIN
    SET @cmd = 'EXEC xp_cmdshell ''del ' + @file_path + ''''
    EXEC(@cmd)

    FETCH NEXT FROM file_cursor INTO @file_path
END

CLOSE file_cursor

DEALLOCATE file_cursor