Question

I’m writing a homework for my RDBMS class, I need to perform CRUD operations on quite simple domain, which is cyber sport championship.
Students are required to use ADO.NET. My question is how can I solve bidirectional relationship, for example 1:m (every championship has many matches, but every match belongs to only one exact championship)? It seems to me that there must be some technique for that.
And the most interesting part for me is – how does ORM like EF or NHibernate solve this situation?

Answer 1

In NHibernate, it is quite simple and straight-forward. Here’s how the domain classes would look, followed by fluent mappings. This assumes you would use NHibernate to generate your schema. If you are mapping a legacy database, it is simple to set the column names and table names used.

public class Championship {
  public virtual int Id { get; set; }
  public virtual IList<Match> Matches { get; set; }
}


public class Match {
  public virtual int Id { get; set; }
  public virtual Championship Champioship { get; set; }
}


public class ChampionshipMap : ClassMap<Championship> {
  public ChampionshipMap() {
    Id(x => x.Id);
    HasMany(x => x.Matches);
  }
}


public class MatchMap : ClassMap<Match> {
  public MatchMap () {
    Id(x => x.Id);
    References(x => x.Championship);
  }
}