How do I programmatically disable/enable a block?

Question

I have the following code but its not disbling the block. It remains active and visible on the sidebar where i have placed it.

$theme="themename";
$block="client-block-1938";
$module="modulename";
$region="right_top_box";
db_merge('block')
        ->key(array('theme' => $theme, 'delta' => $block, 'module' => $module))
        ->fields(
                       array(
                              'region' => $region,
                              'status' => 0,
                              'visibility' => 0,
                           )
             )
->execute();
cache_clear_all();

Answer 1

Use db_update.

db_update('block')
   ->fields(array(
     'status' => 0,
     'weight' => -10,
     'region' => 'disabled',
   ))
   ->condition('module', 'modulename')
   ->condition('delta', 'modulename_delta')
   ->execute();

Answer 2

I think this should work.

     db_update('block')
        ->fields(array(
          'status' => 0,
          'weight' => -10,
          'region' => 'disabled',
        ))
     ->condition('module', $module)
     ->condition('delta', $delta)
     ->condition('theme', $theme)     
      ->execute();

    cache_clear_all();