更新时MySQL语法错误

请确保使用值更新using IN()子句varchar.请查看此内容以获取更多详

所以你应该用它包装'.

$result_update = mysqli_query($datba1,"UPDATE wall_hashtags  SET 
                 numbr=numbr-1 WHERE htag IN ('".implode("','", $delhash)."')")
                or die(mysqli_error($datba1));