如何使用Entity Framework删除多行？

Question

I have this code but it doesn't work :

public bool DeleteAccess(int _UserID, IEnumerable<int> _ModulID)
{
    MPortalContext db=new MPortalContext();
    foreach (var item in _ModulID)
    {
        var validation = db.WebSite_PermissionDB.Where(x => x.UserID == _UserID && x.ModuleID == item);
        db.WebSite_PermissionDB.Remove(validation);
    }
    db.SaveChanges();
    return true;
}

my (_ModulID) is a collection of ids that i filter them and then with foreach delete them but it doesn't work ??

Answer 1

one way to delete is

context.Database.SqlQuery<WebSite_PermissionDB>(
  "DELETE FROM Users WHERE UserID = @userId  ",
  new [] { new SqlParameter("@userId ", 1) }
);

Answer 2

First get the all entities that mathces with your condition, then use RemoveRange method:

var entities = db.WebSite_PermissionDB
           .Where(x => x.UserID == _UserID && _ModulID.Contains(x.ModuleID));

db.WebSite_PermissionDB.RemoveRange(entities);

db.SaveChanges();

Also you might want to use using statement in order to make sure that your DbContext is Disposed properly.

using(MPortalContext db = new MPortalContext())
{ 
     ...
} 

Answer 3

var distinctResult = db.WebSite_PermissionDB.Distinct();
db.WebSite_PermissionDB.RemoveRange(db.WebSite_PermissionDB.Except(distinctResult));
db.SaveChanges();

Answer 4

    MPortalContext db=new MPortalContext();
    foreach (var item in _ModulID)
    {
        var validation = db.WebSite_PermissionDB.Where(x => x.UserID == _UserID && x.ModuleID == item).FirstOrDefault();
        db.WebSite_PermissionDB.Remove(validation);
        db.SaveChanges();
    }  
    return true;

I forget use .FirstOrDefault(); now correct. Thank friends.