EDIT

<?php

// $Id$

/**

 * Implementation of hook_install().

 */

function cdm_dataportal_install(){

   db_query(_get_sql_fix_module_weight());

}

/**

 * Implementation of hook_uninstall().

 */

function cdm_dataportal_uninstall(){

   cdm_delete_all_cdm_nodes();

}

/**

 * Implementation of hook_api_update_N().

 *

 * Database updates consist of 3 parts:

 *    1 digit for Drupal core compatibility

 *    1 digit for your module's major release version (e.g. is this the 5.x-1.* (1) or 5.x-2.* (2) series of your module?)

 *    2 digits for sequential counting starting with 00

 * The 2nd digit should be 0 for initial porting of your module to a new Drupal core API.

 *

 * Update 1 for version 5.x-1.0

 */

function cdm_dataportal_update_5101() {

	$items = array();

	$items[] = update_sql(_get_sql_fix_module_weight());

	return $items;

}

/**

 * Implementation of hook_api_update_N().

 *

 * Database updates consist of 3 parts:

 *    1 digit for Drupal core compatibility

 *    1 digit for your module's major release version (e.g. is this the 5.x-1.* (1) or 5.x-2.* (2) series of your module?)

 *    2 digits for sequential counting starting with 00

 * The 2nd digit should be 0 for initial porting of your module to a new Drupal core API.

 *

 * Update 2 for version 5.x-1.0

 */

function cdm_dataportal_update_5102() {

  $items = array();

  $items[] = _remove_variable('cdm_currentSecRef');

  if(variable_get('distribution_sort', false) == 1){

	  $items[] = _modify_variable('distribution_sort', 'HIDE_TDWG2');

  } else {

  	$items[] = _modify_variable('distribution_sort', 'NO_SORT');

  }

  $items[] = _create_variable('cdm_dataportal_geoservice_distributionOpacity', '1.0');

  $items[] = _create_variable('cdm_dataportal_geoservice_legendOpacity', '0.75');

  return $items;

}

/**

 * Implementation of hook_api_update_N().

 *

 * Database updates consist of 3 parts:

 *    1 digit for Drupal core compatibility

 *    1 digit for your module's major release version (e.g. is this the 5.x-1.* (1) or 5.x-2.* (2) series of your module?)

 *    2 digits for sequential counting starting with 00

 * The 2nd digit should be 0 for initial porting of your module to a new Drupal core API.

 *

 * Update 1 for version 5.x-3.0

 */

function cdm_dataportal_update_5301() {

  $items = array();

  // add new default to

  $annotation_types_filter = variable_get('annotations_types_as_footnotes', FALSE);

  if($annotation_types_filter) {

    $annotation_types_filter['NULL_VALUE'] = 'NULL_VALUE';

  }

  $items[] = _modify_variable('annotations_types_as_footnotes', $annotation_types_filter);

  return $items;

}

// ------------------------- SQL  Scripts ------------------------ //

function _get_sql_fix_module_weight() {

	return  "UPDATE {system} SET weight = 20 WHERE name = 'cdm_dataportal'";

}

function _rename_variable($old_name, $new_name) {

	$success = FALSE;

	$value = variable_get($old_name, FALSE);

	variable_del($old_name);

	if($value !== FALSE){

		variable_set($new_name, $value);

		$success = variable_get($new_name, FALSE) === $value;

	} else {

		$success = TRUE;

	}

	return array('success' => $success, 'query' => "Renaming variable $old_name to $new_name");

}

function _remove_variable($name) {

  variable_del($name);

  return array('success' => TRUE, 'query' => "Removing variable $name");

}

function _create_variable($name, $value) {

  variable_set($name, $value);

  return array('success' => TRUE, 'query' => "Creating variable $name new value: $value");

}

function _modify_variable($name, $value_override) {

  /*

   * FIXME take care for correct handling of tree variables

   * for example description_gallery contains the array:

   * Array

			(

			    [cdm_dataportal_show_thumbnail_captions] => 1

			    [cdm_dataportal_media_maxextend] => 120

			    [cdm_dataportal_media_cols] => 4

			)

	 * -----> solutions merge arrays !!!

   */

  return _create_variable($name, $value_override);

}