Creating the model

As always, we should run our existing test suite at the start of our iteration to ensure all of our previously written tests are still passing as expected. By this time, you should be familiar with how to do that, so we will leave it to the reader to ensure that all the unit tests are passing before proceeding.

We first need to create a new table to house our comments. Below is the basic DDL definition for the table that we will be using:

CREATE TABLE tbl_comment
(
  `id` INTEGER NOT NULL PRIMARY KEY AUTO_INCREMENT,
  `content` TEXT NOT NULL,
  `issue_id` INTEGER,
  `create_time` DATETIME,
  `create_user_id` INTEGER,
  `update_time` DATETIME,
  `update_user_id` INTEGER  
)

As each comment belongs to a specific issue, identified by the issue_id, and is written by a specific user, indicated by the create_user_id identifier, we also need to define the following foreign key relationships:

ALTER TABLE `tbl_comment` ADD CONSTRAINT `FK_comment_issue` FOREIGN KEY (`issue_id`) REFERENCES...