LINQ查询正在删除多行而不是单行

Question

I have tried the following:

var itemtoremove = db.ItemGroups.Single(x => x.ID == _id);
if (itemtoremove != null)
{
    db.ItemGroups.Remove(itemtoremove);
    db.SaveChanges();
}

The query 'works' but it deletes more than one row! Any ideas? The table itself is part of a set or really terrible tables, but I've got to use them. Can having multiple keys on a table affect what EF does?

Thanks folks.

Answer 1

If the enitity has a navigation property and you have not set CascadeOnDelete(false); you could potentially remove more than one item.

//check item group for duplicates (just as a test)
var items = db.ItemGroups.Where(x => x.ID == _id); //breakpoint here to make sure there is only one match. If there is only one then you are deleting a linked item to the entity you are deleting.

var itemtoremove = db.ItemGroups.Single(x => x.ID == _id);
if (itemtoremove != null)
{
    db.ItemGroups.Remove(itemtoremove);
    db.SaveChanges();
}

Answer 2

I found a resolution. I think with the table having 2 PK's setup on it (both on CHAR fields) was causing EF to become confused. The table goes back years and it is part of a group of tables that do not relate to one another properly. It's pretty poor but that's another story!

So, I started from scratch again:

After re-importing the table in it's original format I did the following:

• Removed the PK on 'GroupID' (should never have been a PK)
• Added an ID column, set it as 'IsIdentity' so it will auto-generate an ID

• refreshed my EF Model to include:

   [DatabaseGenerated(DatabaseGeneratedOption.Identity)] public int ID { get; set; } 

Now only the one correct row is removed when the SaveChanges is applied.

Thanks for your suggestions folks!