begin tran
CREATE TABLE Locations
(
	Id INT PRIMARY KEY,
	Latitude FLOAT,
	Longitude FLOAT
)

CREATE TABLE [Credentials]
(
	Id INT PRIMARY KEY,
	Email VARCHAR(30),
	Password VARCHAR(30)
)

CREATE TABLE Chats
(
	Id INT PRIMARY KEY,
	Title VARCHAR(32),
	StartDate DATE,
	IsActive BIT
)

CREATE TABLE Users
(
	Id INT PRIMARY KEY,
	Nickname VARCHAR(25),
	Gender CHAR(1),
	Age INT,
	LocationID INT FOREIGN KEY REFERENCES Locations(Id),
	CredentialID INT FOREIGN KEY REFERENCES [Credentials](ID) UNIQUE
)

CREATE TABLE [Messages]
(
	Id INT PRIMARY KEY,
	Content VARCHAR(200),
	SentOn DATE,
	ChatId INT FOREIGN KEY REFERENCES Chats(Id),
	UserId INT FOREIGN KEY REFERENCES Users(Id)
)

CREATE TABLE UsersChats
(
	ChatId INT REFERENCES Chats(Id),
	UserId INT REFERENCES Chats(Id),
	PRIMARY KEY (ChatId, UserId)
)
rollback;