一个实体对应多个DBSets

1. 可以使用继承来实现一个基类，然后派生多个子类对应不同的DBSet，并在每个子类的构造函数中指定对应的DBSet。示例如下：

public abstract class BaseEntity
{
    public int Id { get; set; }
    // other common properties
}

public class Entity1 : BaseEntity
{
    public Entity1(DbContext1 dbContext1)
    {
        this.DbContext = dbContext1;
        DbSet = dbContext1.Entity1s;
    }

    public DbContext1 DbContext { get; }
    public DbSet<Entity1> DbSet { get; }
    // other properties unique to Entity1
}

public class Entity2 : BaseEntity
{
    public Entity2(DbContext2 dbContext2)
    {
        this.DbContext = dbContext2;
        DbSet = dbContext2.Entity2s;
    }

    public DbContext2 DbContext { get; }
    public DbSet<Entity2> DbSet { get; }
    // other properties unique to Entity2
}

2. 另一种方法是使用泛型，将DbContext和DbSet通过泛型参数传递进来。示例如下：

public class BaseEntity<TContext, TEntity> where TContext : DbContext where TEntity : BaseEntity<TContext, TEntity>
{
    public int Id { get; set; }
    // other common properties

    public static DbSet<TEntity> Set(TContext context) => context.Set<TEntity>();
}

public class Entity1 : BaseEntity<DbContext1, Entity1>
{
    // other properties unique to Entity1
}

public class Entity2 : BaseEntity<DbContext2, Entity2>
{
    // other properties unique to Entity2
}

然后在代码中可以这样使用：

using (var context1 = new DbContext1())
{
    var entity1 = new Entity1();
    context1.Entity1s.Add(entity1);
    context1.SaveChanges();
}

using (var context2 = new DbContext2())
{
    var entity2 = new Entity2();
    context2.Entity2s.Add(entity2);
    context2.SaveChanges();
}