Because, your database table doesn't accepts null value for feedback column. Check this code very carefully:
public class DAL
{
public bool insert(Bo aa)
{
if (aa.Equals(null))
{
return false;
}
else
{
using (problemEntities1 context = new problemEntities1())
{
Table1 tt = new Table1();
context.AddToTable1(tt);
context.SaveChanges();
}
return true;
}
}
}
If object aa is not null then the debugger will move to else block. You are not inserting the value of aa in your table. You are just creating the object of your Table1(it'll have all the column values as null) and directly instering that onject to the context. Try this:
Table1 tt = new Table1();
tt.Status = aa.Status;
tt.Feedback = aa.Feedback;
context.AddToTable1(tt);
context.SaveChanges();
--Amit