uploading an image (BLOB) to mysql

I updated the default collation and default char set but still have the issue. I think the problem is with the SQL 'update'. This is what I am using


        $BLOB_insert = array(
            "id" => $primary_key,
            "img_BLOB" => $data
        );

$this->db->update('word', $BLOB_insert);

I see this error in the log:
ERROR - 2021-03-24 18:13:03 --> Query error: Duplicate entry '47' for key 'word.PRIMARY' - Invalid query: UPDATE `word` SET `id` = 47, `img_BLOB` =

But I am trying to update id=47! It is true that the data in the blob is showing lots of '?' chars, but now I am thinking that is not the problem, the problem is the update command.

proof that an old dog can learn new tricks