Creating read only Sql Server login

-- Configure test database
USE master;

CREATE DATABASE TestDBR;
USE TestDBR;
CREATE TABLE Inventory (id INT, name NVARCHAR(50), quantity INT)
INSERT INTO Inventory VALUES (1, 'banana', 150); INSERT INTO Inventory VALUES (2, 'orange', 154);

-- Grant public master access
USE master;
CREATE LOGIN reader1 WITH password='0plmNJI9';
CREATE USER reader1 FROM LOGIN reader1;

-- Create user in database that should have read only access
USE TestDBR;
CREATE USER reader1 FROM LOGIN reader1;
EXEC sp_addrolemember 'db_datareader', 'reader1';

-- Verification
USE TestDBR;

-- Should return new role
SELECT SUSER_NAME(), user_name();
-- Should fail to insert value
INSERT INTO Inventory VALUES (1, 'banana', 150); INSERT INTO Inventory VALUES (2, 'orange', 154);
-- Should fail to delete
DELETE FROM Inventory WHERE name = 'banana';