PHP/MySQL insert string into database

Question

I'm trying to insert multiple different words into a database if they are not already in the database. I'm getting the text from a textfield where the user inputs multiple categories. I want to split the text being passed from this textfield by comma and insert it individually into the database if it's not already in it. Currently nothing is being input into the database. Thanks in advance for your help!

Here is my code to split the textfield data and insert into the database:

$category = trim($_POST['category']);

$cat2 = explode(',', $category);
foreach ($cat2 as $new_interest)
{
$insert_user_interests = sprintf("INSERT INTO interests IF NOT EXISTS name = '". $new_interest . "'" .
                                                 "(name) " .
                            "VALUES ('%s');",
                             mysql_real_escape_string($new_interest));
mysql_query($insert_user_interests);
}

Answer 1

This is your insert statement:

INSERT INTO interests IF NOT EXISTS name = '". $new_interest . "'" .
                                             "(name) " .
                        "VALUES ('%s')

As far as I'm aware, this is not valid insert syntax. (The documentation is here.) I think you are confusing it with the create table syntax. Instead, use ignore and something like:

INSERT IGNORE INTO interests(name) VALUES(". $new_interest . "')" 

EDIT:

Right, if you don't want to insert duplicates, then create a unique index on name:

create index unique interests_name on interests(name);

Then the above query will do what you want.