如何在没有主键实体框架的情况下映射表

Question

I'm using Entity Framework to map some tables, but I can't do this unless I declare some column as the primary key.

The problem here is that my table in my database don't have a primary key and has millions of rows. I don't have permission to create a new Id column.

[Table("MYTABLE")]
public class myTable
{
    [Column("NUMX")]
    public virtual string NumX { get; set; }

    [Column("NAME")]
    public virtual string Name { get; set; }

    [Column("AGE")]
    public virtual int AGE { get; set; }
}

Obs: If I add the [Key] attribute to some column like Age , it works, but returns the wrong data.

Is there some way to omit the primary key?

Answer 1

Entity Framework requires a primary key unlike SQL.

EF use the primary key to uniquely identify rows (for example when you use .Find() or to perform update operations).

Infact not having a primary key remember a SQL VIEW, where you can only read data .

If any of the columns uniquely identify a certain row set it as a primary key ( it can't be NULL ) also if in Sql it isn't a key. Otherwise if the combination of the columns are uniquely, create a composite key with these columns.

Remember that you should have a primary key in the 99% of cases, when you don't have a primary key you should stop and think if it make sense.

Answer 2

I Figured out the problem. Composite Keys works for me: eg: In my Context I defined some keys , not only one, but three keys:

public class MyContext : DbContext
{
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        **//Here is the secret**
        modelBuilder.Entity<MyModel>().HasKey(x => new { x.NumX, x.Name,x.Age});
    }
}