dont use numRows when it's not needed since it can be expensive

lib/appconfig.php

@@ -93,14 +93,12 @@ class OC_Appconfig{
 		// At least some magic in here :-)
 		$query = OC_DB::prepare( 'SELECT configvalue FROM *PREFIX*appconfig WHERE appid = ? AND configkey = ?' );
 		$result = $query->execute( array( $app, $key ));
-
-		if( !$result->numRows()){
+		$row = $result->fetchRow();
+		if($row){
+			return $row["configvalue"];
+		}else{
 			return $default;
 		}
-
-		$row = $result->fetchRow();
-
-		return $row["configvalue"];
 	}
 
 	/**

lib/group/database.php

@@ -56,7 +56,7 @@ class OC_Group_Database extends OC_Group_Backend {
 		$query = OC_DB::prepare( "SELECT gid FROM `*PREFIX*groups` WHERE gid = ?" );
 		$result = $query->execute( array( $gid ));
 
-		if( $result->numRows() > 0 ){
+		if( !$result->fetchRow() ){
 			// Can not add an existing group
 			return false;
 		}

lib/preferences.php

@@ -116,14 +116,13 @@ class OC_Preferences{
 		// Try to fetch the value, return default if not exists.
 		$query = OC_DB::prepare( 'SELECT configvalue FROM *PREFIX*preferences WHERE userid = ? AND appid = ? AND configkey = ?' );
 		$result = $query->execute( array( $user, $app, $key ));
-
-		if( !$result->numRows()){
+		
+		$row = $result->fetchRow();
+		if($row){
+			return $row["configvalue"];
+		}else{
 			return $default;
 		}
-
-		$row = $result->fetchRow();
-
-		return $row["configvalue"];
 	}
 
 	/**

lib/user/database.php

@@ -106,8 +106,8 @@ class OC_User_Database extends OC_User_Backend {
 		$query = OC_DB::prepare( "SELECT uid FROM *PREFIX*users WHERE uid LIKE ? AND password = ?" );
 		$result = $query->execute( array( $uid, sha1( $password )));
 
-		if( $result->numRows() > 0 ){
-			$row=$result->fetchRow();
+		$row=$result->fetchRow();
+		if($row){
 			return $row['uid'];
 		}else{
 			return false;