Issues with MySQL Query()

Question

I am trying to learn some MySQL and PhP and am having trouble using the query() method to update my database.

I can fetch() and display the information, so I know my connection is fine, and I've updated in a similar way previously with no issue. I've also double-checked that I'm sending the correct data types, that my names are correct, and that I'm not going over any character limits, so I'm a little at a loss. I used var_dump to check the result of query and keep getting a false boolean.

<?php
if(isset($_POST["submit"])) {

    $title = $_POST["title"];
    $category = $_POST["category"];
    $image = $_FILES["image"]["name"];
    $text = $_POST["text"];

    $targetFile = "upload/".basename($image);

    //validations

    if(empty($title)) {
        $_SESSION["errorMessage"] = "A title is required.";
        redirect("editPost.php");
    } else if (strlen($title) > 49) {
        $_SESSION["errorMessage"] = "Post title can not be greater than 50 characters.";
        redirect("editPost.php");
    } else if (strlen($title) <= 5) {
        $_SESSION["errorMessage"] = "Post title must be greater than 5 characters.";
        redirect("editPost.php");
    } else if (strlen($text) > 9999) {
        $_SESSION["errorMessage"] = "Post content must be under 10000 characters.";
        redirect("editPost.php");
    } else {

        $sql = "
    UPDATE posts 
       SET title='$title'
         , category='$category'
         , image='$image' 
           post='$text' -- er, something missing here
     WHERE id = '$searchQueryParameter'
    ";
        $execute = $connectDB -> query($sql);
        var_dump($execute);
        move_uploaded_file($_FILES["image"]["tmp_name"], $targetFile);
        /*          if ($execute) {
                    $_SESSION["successMessage"] = "Post updated successfully.";
                    redirect("posts.php");
                                } else {
                    $_SESSION["errorMessage"] = "Something went wrong. Please try again.";
                    redirect("posts.php");
                                } */
    }
}
?>

Any help would be appreciated, thanks!