Index: wp-includes/version.php
===================================================================
--- wp-includes/version.php	(revision 3022)
+++ wp-includes/version.php	(working copy)
@@ -3,6 +3,6 @@
 // This just holds the version number, in a separate file so we can bump it without cluttering the SVN
 
 $wp_version = '1.6-ALPHA-2-still-dont-use';
-$wp_db_version = 2966;
+$wp_db_version = 3022;
 
 ?>
\ No newline at end of file
Index: wp-admin/upgrade-functions.php
===================================================================
--- wp-admin/upgrade-functions.php	(revision 3022)
+++ wp-admin/upgrade-functions.php	(working copy)
@@ -33,9 +33,12 @@
 	if ( $wp_current_db_version < 2966 )
 		upgrade_160();
 
+	if ( $wp_current_db_version < 3022 )
+		upgrade_3022();
+
 	save_mod_rewrite_rules();
 	
-	update_option('db_version', $wp_db_version);
+    update_option('db_version', $wp_db_version);
 }
 
 function upgrade_100() {
@@ -302,6 +305,12 @@
 	}
 }
 
+function upgrade_3022() {
+	global $wpdb;
+    // update link categories table to use enums
+    $wpdb->query("ALTER TABLE $wpdb->linkcategories MODIFY COLUMN sort_order ENUM('id','name','rand','rating','updated','url') DEFAULT 'rand'");
+}
+    
 // The functions we use to actually do stuff
 
 // General
Index: wp-admin/upgrade-schema.php
===================================================================
--- wp-admin/upgrade-schema.php	(revision 3022)
+++ wp-admin/upgrade-schema.php	(working copy)
@@ -39,7 +39,7 @@
   show_description enum('Y','N') NOT NULL default 'N',
   show_rating enum('Y','N') NOT NULL default 'Y',
   show_updated enum('Y','N') NOT NULL default 'Y',
-  sort_order varchar(64) NOT NULL default 'rand',
+  sort_order enum('id','rand','name','url','rating','updated') default 'rand',
   sort_desc enum('Y','N') NOT NULL default 'N',
   text_before_link varchar(128) NOT NULL default '<li>',
   text_after_link varchar(128) NOT NULL default '<br />',