Generic Repository example. Can be used as a single repository that will work for every entity.

GenericRepository.cs

using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;

namespace mycompany.employee_manager.Core.Data.Repository
{
    public class GenericRepository<TEntity>
        where TEntity : class
    {
        internal ProvausioEmployeeManagerContext Context;
        internal DbSet<TEntity> DbSet;

        public GenericRepository() : this(new MyApplicationContext()) { } 

        public GenericRepository(MyApplicationContext context)
        {
            Context = context;
            DbSet = context.Set<TEntity>();
        }

        public virtual IEnumerable<TEntity> Get()
        {
            IQueryable<TEntity> query = DbSet;
            return query.ToList();
        }

        public virtual TEntity GetById(object id)
        {
            return DbSet.Find(id);
        }

        public virtual void Insert(TEntity entity)
        {
            DbSet.Add(entity);
        }

        public virtual void Delete(object id)
        {
            var toDelete = DbSet.Find(id);
            Delete(toDelete);
        }

        public virtual void Delete(TEntity entity)
        {
            if (Context.Entry(entity).State == EntityState.Detached)
            {
                DbSet.Attach(entity);
            }
            DbSet.Remove(entity);
        }

        public virtual void Update(TEntity entity)
        {
            DbSet.Attach(entity);
            Context.Entry(entity).State = EntityState.Modified;
        }
    }
}