fixing undefined index notice

Question

I'm getting an undefined index notice, but can't figure out how to fix it.

Notice: Undefined index: id in /home/jharvard/vhosts/localhost/html/book_details.php on line 10

This is the code that's having problems:

    // query for the listing
$listing = query("SELECT name, author, id, edition, price, course, date FROM books WHERE submission = ?", $_GET["submission"]); 

// query for the email of the seller
$seller = query("SELECT email FROM users WHERE id = ?", $listing["id"]);

Can anyone help? Thank you very much.

Is query a custom function or does this belong to a specific database library? Try using using `print_r( $listing )` to see what values `$listing` has. — Jared, Dec 06 '12 at 19:53
What is `query()`? Does it return the *result* of the query? — gen_Eric, Dec 06 '12 at 19:53
Do a `var_dump($listing)` first and see what you're really getting back. — Marc B, Dec 06 '12 at 19:57

score 1 · Answer 1 · answered Dec 06 '12 at 19:53

The problem is that the array returned from your first query, $listing doesn't have an element with the key id.

I suspect this would happen if there was no record in the database for whatever was passed in as the submission GET parameter. Hard to say for sure though without knowing how the query() function was written.

fixing undefined index notice

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