To completely remove the column (and data in it), use the DropColumn() method. To accomplish this, create a new migration add-migration unwantedColumnCleanup and include the necessary code in the up() method, and then update-database .
To remove a table, simply remove the corresponding DbSet<MyClass> and any references to that class in other parts of your model and EF will add a DropTable to the migration automatically. If you are no longer using the class for non-Entity Framework purposes you can delete it.
It's not necessary to query the object first, you can attach it to the context by its id. Like this:
var employer = new Employ { Id = 1 };
ctx.Employ.Attach(employer);
ctx.Employ.Remove(employer);
ctx.SaveChanges();
Alternatively, you can set the attached entry's state to deleted :
var employer = new Employ { Id = 1 };
ctx.Entry(employer).State = EntityState.Deleted;
ctx.SaveChanges();
You can use SingleOrDefault
to get a single object matching your criteria, and then pass that to the Remove
method of your EF table.
var itemToRemove = Context.Employ.SingleOrDefault(x => x.id == 1); //returns a single item.
if (itemToRemove != null) {
Context.Employ.Remove(itemToRemove);
Context.SaveChanges();
}
var stud = (from s1 in entities.Students
where s1.ID== student.ID
select s1).SingleOrDefault();
//Delete it from memory
entities.DeleteObject(stud);
//Save to database
entities.SaveChanges();
Employer employer = context.Employers.First(x => x.EmployerId == 1);
context.Customers.DeleteObject(employer);
context.SaveChanges();
I am using entity framework with LINQ. Following code was helpful for me;
1- For multiple records
using (var dbContext = new Chat_ServerEntities())
{
var allRec= dbContext.myEntities;
dbContext.myEntities.RemoveRange(allRec);
dbContext.SaveChanges();
}
2- For Single record
using (var dbContext = new Chat_ServerEntities())
{
var singleRec = dbContext.ChatUserConnections.FirstOrDefault( x => x.ID ==1);// object your want to delete
dbContext.ChatUserConnections.Remove(singleRec);
dbContext.SaveChanges();
}
More generic approuch
public virtual void Delete<T>(int id) where T : BaseEntity, new()
{
T instance = Activator.CreateInstance<T>();
instance.Id = id;
if (dbContext.Entry<T>(entity).State == EntityState.Detached)
{
dbContext.Set<T>().Attach(entity);
}
dbContext.Set<T>().Remove(entity);
}
With Entity Framework 6, you can use Remove
.
Also it 's a good tactic to use using
for being sure that your connection is closed.
using (var context = new EmployDbContext())
{
Employ emp = context.Employ.Where(x => x.Id == id).Single<Employ>();
context.Employ.Remove(emp);
context.SaveChanges();
}
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