Mysqli insert id returning null

Question

$S = "INSERT INTO ". TBD ." (NODE, AV, BV) VALUES ('15', '$name', '$email')";
$Q = $CONN->query($S);
$M = $Q->insert_id;

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$M returns NULL not 0

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The above script runs the query fine, but will not return the unique ID generated. The table, definitely has a auto increment and is a primary key. I have used the script elsewhere and works fine.

So I have no idea why its returning NULL now.

Answer 1

I think you are calling insert_id wrong. Try this:

$S = "INSERT INTO ". TBD ." (NODE, AV, BV) VALUES ('15', '$name', '$email')";
$Q = $CONN->query($S);
$M = $CONN->insert_id;