Question

I have a mysqli function that is inserting a row into a table. I’m getting back the error

Warning: mysqli_stmt::bind_result(): Number of bind variables doesn't match number of 
fields in prepared statement

This is odd to me since I thought insert nto returns true or false. Here is the function that is using the sql statement.

function add_project_deadline ($mysqli, $project_id, $deadline) {


if ($stmt = $mysqli->prepare("INSERT INTO `project_deadline` (project_id, deadline) 
    VALUES (?, ?)")){
    $stmt->bind_param('is', $project_id, $deadline);
    $stmt->execute();
    $stmt->bind_result($return);
    $stmt->close();
    return $return;
} else {return false;}  

}

My question is why am I getting this bind_result error and how do I fix it.

Answer 1

Since you are executing an INSERT query which doesn’t have any results, you don’t need or use bind_result for fetching data. bind_result is for binding to columns used in a SELECT statement.

mysqli_stmt::execute() returns true on success or false on failure so simply assign the value of that to your $return variable.

If execute() returns false, the INSERT statement failed for some reason. If it returns true, the INSERT was successful and you can determine the number of rows inserted by looking at the mysqli_stmt::$affected_rows property of your statement object.

That’s why you’re getting that error, hope it helps. You can find most of this information on the manual page for mysqli_stmt::execute().