get success/failure response from mysqli_query

Question

I'm gathering info from a user and then adding them to a table.

$insert = "INSERT INTO jos_activeagents (RINGPHONE, AGENTUID, FNAME, LNAME) VALUES ('(618) 717-2054','".$result['AGTBRDIDMM']."','".$result['AGTFNAME']."','".$result['AGTLNAME']."')";

$set = mysqli_query($link,$insert);

AGENTUID is a unique key. If a user tries to submit with a duplicate unique key, I get an error (of course).

Now, how would I go about knowing if and when an error occurred and then putting a response back to the page? I know of mysqli_get_warnings(), but the PHP manual doesn't show any examples.

I have also tried looking for the AGENTUID in the table first:

$check = "SELECT * FROM jos_activeagents WHERE AGENTUID = '".$agt."'";

$runcheck = mysqli_query($link,$check);

$rescheck = mysqli_fetch_assoc($runcheck);

if($rescheck != null){

    echo 'This Agent ID is already enrolled.'

}

But this seems sloppy. Is there a better way do this?

Answer 1

You can use mysqli_error() to see if an error occurred

if (mysqli_error($runcheck ))
{
   // an error eoccurred
}

In your particular example you're better of checking if the row exists before doing the insert. Your example is close but would better using mysqli_num_rows():

$check = "SELECT * FROM jos_activeagents WHERE AGENTUID = '".$agt."'";
$runcheck = mysqli_query($link,$check);
if (mysqli_num_rows($runcheck) > 0)
{
    // username in use
}