File Upload - General Questions

[phpstuff]

On pg 347 in the 4th TIPS from the top it is mentioned that the move_uploaded_file function will overwrite an existing file with the same name. 

 

Questions:

 

1.  How does this work with uploading to folders VS. uploading to database?

 

2.  In a database would it not matter as long as it is a single file being added to a unique user_id?

 

3.  What would you do if there are multiple files and you want to prevent this from happening in a database?  In a folder?

 

 

I'm guessing that you somehow concatenate a random # to the filename?  Not sure but I'd sure love to have more insight here as this is something that I plan on implementing in future sites (user can upload 10 photos to a single page, etc).

 

Thanks!

 

 

[Larry]

I'm really not sure what you mean by "uploading to a database". The move_uploaded_file() function only moves files around within the file system. It can't touch the database.

[phpstuff]

For example, if you insert files into a DB and the files have the same name, would it not matter because the index is unique?

 

Say there are no records in the database and only Row 1 has a file uploaded:

 

Row 1   data_id       photo_of_the_desert.jpg

 

Then somebody else (or that same person) adds another photo and it just so happens to have that same exact file name:

 

Row 2   data_id       photo_of_the_desert.jpg

 

 

I'm assuming each row would have its own unique identifier (data_id might increase incrementally/change for each uploaded file?).

 

I was more or less just curious how uploading files to folders compares to using a DB for storage - advantages, disadvantages, and when you should use one or the other. 

[Larry]

Okay, to be clear here, you're not inserting files into the database. You're inserting records about files. Although it may seem like semantics, there's a big difference. If you have a UNIQUE restriction on the file name column in the database, then no two users could upload a file with the same name. That's why I wouldn't place a UNIQUE restriction on the file name column in the database. 

 

I often store the file itself--the actual file data--on the file system, using a unique name. I store information about the file, including its original name, in the database. You can store files in a database (store the actual file data there), but that's not often a good solution.

[phpstuff]

Perfect.  Thank you for clearing that up.  That does make sense and gives me a good starting point to research further.

 

Thanks!