SELECT 'CREATE DATABASE main'
WHERE NOT EXISTS (SELECT FROM pg_database WHERE datname = 'main')\gexec
CREATE TABLE Persons (
    PersonID SERIAL PRIMARY KEY,
    LastName varchar(255),
    FirstName varchar(255),
    Address varchar(255),
    City varchar(255) DEFAULT 'Belfast'
);
CREATE TABLE Tasks (
    TaskID SERIAL PRIMARY KEY,
    PersonID INT,
    TaskName varchar(255),
    CONSTRAINT fkPersons
        FOREIGN KEY(PersonID)
	    REFERENCES Persons(PersonID)
);
CREATE TABLE Products (
    ProductID SERIAL PRIMARY KEY,
    ProductName varchar(255)
);
CREATE TABLE Products_Tasks (
    ProductID INT NOT NULL,
    TaskID INT NOT NULL,
    CONSTRAINT fkProducts
        FOREIGN KEY(ProductID)
	    REFERENCES Products(ProductID),
    CONSTRAINT fkTasks
        FOREIGN KEY(TaskID)
	    REFERENCES Tasks(TaskID),
    PRIMARY KEY (ProductID, TaskID)
);
INSERT INTO Persons (FirstName, LastName, Address, City) VALUES ('Mike', 'Hughes', '123 Fake Street', 'Belfast');
INSERT INTO Tasks (PersonID, TaskName) VALUES (1, 'assembling');
INSERT INTO Tasks (PersonID, TaskName) VALUES (1, 'processing');
INSERT INTO Products (ProductName) VALUES ('Computers');
INSERT INTO Products (ProductName) VALUES ('Laptops');
INSERT INTO Products (ProductName) VALUES ('Chairs');
INSERT INTO Products_Tasks (ProductID, TaskID) VALUES (1, 1);
INSERT INTO Products_Tasks (ProductID, TaskID) VALUES (2, 1);
INSERT INTO Products_Tasks (ProductID, TaskID) VALUES (3, 1);
INSERT INTO Products_Tasks (ProductID, TaskID) VALUES (1, 2);