HI我有兩個表(電影Movy實體和生產者爲生產者)。電影中有一個生產者和生產者有很多movies.here是ER診斷 Picture: ER DiagramDataGridView中丟失的一些對象
當我在我的DataGridView的數據索裏設置爲ctx.Movies.ToList()的一些電影中可是沒有任何生產商的名單。即使它在數據庫中不爲空。 Picture:Program with missing producer
//Movie Entity Class
public partial class Movy
{
public short VideoCode { get; set; }
public string MovieTitle { get; set; }
public string MovieType { get; set; }
public string Rating { get; set; }
public Nullable<float> RentalPrice { get; set; }
public string ProducerID { get; set; }
public string Director { get; set; }
public string Media { get; set; }
public Nullable<short> TotalStock { get; set; }
public Nullable<short> NumberRented { get; set; }
public virtual Producer Producer { get; set; }
}
}
//Producer Entity Class
public partial class Producer
{
public Producer()
{
this.Movies = new HashSet<Movy>();
}
public string ProducerID { get; set; }
public string ProducerName { get; set; }
public string CountryCode { get; set; }
public virtual ICollection<Movy> Movies { get; set; }
}
// MyDBEntities ctx
public partial class MYDBEntities : DbContext
{
public MYDBEntities()
: base("name=MYDBEntities")
{
}
public virtual DbSet<Movy> Movies { get; set; }
public virtual DbSet<Producer> Producers { get; set; }
}
//this is my function in windows form which is having some producer missing in movie datalist. i have added the picture of output
private void Form1_Load(object sender, EventArgs e)
{
MYDBEntities ct = new MYDBEntities();
dataGridView1.DataSource = ct.Movies.ToList();
}
P.S:[圖片:數據庫數據]
/* i checked each product and its producer. some producer is null there.
even though its not null in database(I have uploaded db pic) [3]*/
List<Movy> ls = ct.Movies.ToList();
foreach(Movy mov in ls)
{
//some mov.Producer is null here.
}
如果您直接對數據庫運行一個TSQL查詢,你會看到什麼? 'SELECT * from [Producer] WHERE ProducerId like'%Universal%'' –
它給了我一個名爲universal的製作人。 –