[feature] design the database table schema

[zhicheng-ning]

We previously provided an API interface dataset, but now we need to access the data to the database because of the needs of business. So we should consider which table schema is more suitable.

[zhicheng-ning]

ordinary table structure may be like this:

• org_name: organization name
• repo_name: repo name
• t_month: a certain month
• type: metric type such as activity, open_rank, bus_factor
• t_value: corresponding metric value

  create table od_api.repo_metric
  (
  id        int auto_increment primary key,
  org_name  varchar(200) not null,
  repo_name varchar(200) not null,
  t_month     date         not null,
  type      varchar(50)  not null,
  t_value     double       null
  );