Checking if a variable from an array already exsists in a table

dearsina

Hey,

I'm fairly new to the world of PHP/SQL, so there might be an obvious answer to this, I haven't found one though, but if there is, please feel free to just link to that article/post/whatever.

Ok, now to the issue.

I have an array (which incidentally contains a list of files in a given directory, standard format: 1.jpg,2.jpg,etc).

I wish to input this array into a table in an SQL database. I've figured out the inputting bit, but I've realised that if I run the same script twice, the data will be inputted again.

So my issue is, is there a way to make the PHP script check if a array value already exists in a table, and only add it to the table if it doesn't? Let's say (just to make it interesting... 🙂 that the script needs to make sure that the array data is not already implemented in a table called "filename" AND at the same time have the same "foldername" as the data wanted to be inputted? (Basically, different files in different folders might have the same name, but no two files in the same folder have the same name...)

I hope this makes sense. Any help is much appreciated.

sina
norway

yelvington

What you are (I think) trying to do is conditionally insert something if it does not already exist in the database. Right?

Query the database with a SELECT statement first. If there is no match, INSERT.

dearsina

So a SELECT statement that removed already existing items from the query, followed by an INSERT statement which added the ones that aren't there? Makes sense. Any idea how the code would look like...? :-)

I can figure out the INSERT bit, but it's more the excluding SELECT bit I'm a bit lost at.

sina

dearsina

Hey, I figured it out!

Roughly:

Use SELECT, create an array $selectarray from the database
Use $result = array_diff_assoc($selectarray, $alreadymadearray);
to create a third array which only contains items that isn't included in the other two
Use INPUT, input the $result into the database

The beauty of array_diff_assoc() is that is also checks if the index is the same. I've named the index the filename, and the value the folder name, and therefore, I can have files with the same name, but not in the same folder.

dalecosp

That is good!

The only other thing I was thinking was [man]in_array/man, which you still may need or want (might be faster??) if you want to simply check if "file.ext" is already in a database field.

🙂

dearsina

Well, it's not that simple, because there might be several identical "file.ext" in the table "filename" but never duplicate "file.ext"'s with the same value in "foldername". I've read up on in_array(), and you can use it for associative arrays (because I'm looking for two values to be the same; two values which are stored as keys and values of an array: $array(filename => folder) ), but it seems more complicated.

Or maybe I'm thinking that because I've just finished/mastered a script using array_diff_assoc()... :-)

Thanks for your input.
PHP is good, clean fun.

sina
norway