Problem When Assigning a Foreign Key

[chaseman]

I have two tables in my MySQL database:

 

1. user

user_id | firstname | lastname | nickname etc.

 

and

 

2. con (for contribution)

con_id | user_id (foreign key) | name | contribution | category etc.

 

 

Here's how I wanted to solve the problem of assigning the foreign key to the 2nd table (I'm a beginner so bear with me. )

 

When logging in, I assigned the user_id to the session variable like this:

 

		// do the while loop
		while ($assoc = mysqli_fetch_assoc($rows)) {

		// assign database COLUMNS to the variables
		$dbuser_id = $assoc['user_id'];
		$dbuser_name = $assoc['nickname'];
		$dbuser_password = $assoc['password'];

etc.....................


// set a session after login
				$_SESSION['user'] = $dbuser_name . $dbuser_id;

 

 

This prints out the user_id just like I wanted to:

 

echo "Your user_id is: " . $_SESSION['user_id'] = $dbuser_id;

 

Gives:

Your user_id is: 35

 

 

... and this is how the assignment of the foreign key looks like WHILE posting the contribution:

 

$user_id = $_SESSION['user'] = $dbuser_id;

  if (!empty($knuffix_name) && !empty($knuffix_category) && !empty($knuffix_contribution)) {
      // Write the data into the database
      $query = sprintf("INSERT INTO con (con_id, user_id, name, contribution, category, contributed_date) VALUES (' ', '$user_id', '%s', '%s', '%s', now())",
		mysqli_real_escape_string($dbc, $knuffix_name),
		mysqli_real_escape_string($dbc, $knuffix_contribution),
		mysqli_real_escape_string($dbc, $knuffix_category));

 

 

When I now do a contribution through the input areas, nothing gets inserted into the database and I automatically get logged out. Obviously it's not working as I thought it would and I'd like to know why is that?

Notice that if I take the user_id part OUT, it's working again, so the rest of the code must be right then.

 

Another question I have is:

Is this common practice to solve this problem of assigning a foreign key, or is there a better way of doing it?

 

 

[chaseman]

I think the mistake I'm doing is I'm re-assigning the session variable with this:

 

$_SESSION['user'] = $dbuser_id;

 

Now I have only the user_id inside the session variable, and the nickname gets cleared.

 

Is there any way I can tell the session variable to just give me the user_id, but keep the nickname inside the session variable?

 

I think I'll just try assigning two session variables, one for the nickname and one for the id. That may work.

[Jessica]

I think I'll just try assigning two session variables, one for the nickname and one for the id. That may work.

 

Good job thinking it through

[chaseman]

Good job thinking it through

 

Thanks a lot I'm finally learning to become a problem solver just like a real programmer haha..

 

This is how I solved it:

 

$_SESSION['user_name'] = $dbuser_name;
$_SESSION['user_id'] = $dbuser_id;

 

As I said, the mistake I was doing is that I was re-assigning it, and I was thinking I was simply taking out the user_id part of the session variable, but I guess PHP doesn't work that way.

 

 

Now that it's working I hope this is good practice of doing it and I don't encounter vulnerabilities in the future.