CREATE TABLE `Conversations` (
	`Id` int,
	`Subject` varchar(255),
	`CreatedOn` datetime,
	`IsSeen` bool,
	`Sender_Id` int,
	`Receiver_Id` int,
	FOREIGN KEY(`Sender_Id`) REFERENCES `Users` (`Id`),
	FOREIGN KEY(`Receiver_Id`) REFERENCES `Users` (`Id`)
);
CREATE TABLE `Messages` (
	`Id` int PRIMARY KEY,
	`Body` varchar(255),
	`UserAgent` varchar(255),
	`IsRead` bool,
	`SentOn` datetime,
	`Conversation_Id` int,
	`Sender_Id` int,
	`Parent_Id` int,
	FOREIGN KEY(`Conversation_Id`) REFERENCES `Conversations` (`Id`),
	FOREIGN KEY(`Sender_Id`) REFERENCES `Users` (`Id`),
	FOREIGN KEY(`Parent_Id`) REFERENCES `Messages` (`Id`)
);
CREATE TABLE `Users` (
	`Id` int PRIMARY KEY,
	`UserName` varchar(255),
	`DisplayName` varchar(255),
	`HashPassword` varchar(255),
	`Email` varchar(255),
	`...` varchar(255)
);
CREATE TABLE `Attachments` (
	`Id` int PRIMARY KEY,
	`FileName` varchar(255),
	`ContentType` varchar(255),
	`Extension` varchar(255),
	`Size` int,
	`AttachedOn` datetime,
	`Conversation_Id` int,
	`Attacher_Id` int,
	FOREIGN KEY(`Conversation_Id`) REFERENCES `Conversations` (`Id`),
	FOREIGN KEY(`Attacher_Id`) REFERENCES `Users` (`Id`)
);