Having error in updating my record in database my method as follows - asp.net-mvc-4

Question

What I have done wrong in this code ? (I am using MVC4 and EF)
As an example: Please clear this am fresher to use MVC4
EditResponse response = new EditResponse();
try
{
using (WeMatchContext db = new WeMatchContext())
{
B_MEMBER_REGISTER update = new B_MEMBER_REGISTER();
var output = db.B_MEMBER_REGISTER.Where(x => x.MEMBER_ID == model.MEMBER_ID).FirstOrDefault();
if(output != null )
{
update.FIRST_NAME = model.FIRST_NAME;
update.LAST_NAME = model.LAST_NAME;
update.GENDER = model.GENDER;
update.DOB = model.DOB;
int resultcount = db.SaveChanges();
if (resultcount > 0)
{
response.MEMBER_ID = update.MEMBER_ID;
response.ResultCode = 0;
response.Message = "Updated Successfully";
}

Answer 1

You have to attach updated data with the db entity. please try this,
using (WeMatchContext db = new WeMatchContext())
{
var update = db.B_MEMBER_REGISTER.Where(x => x.MEMBER_ID == model.MEMBER_ID).FirstOrDefault();
if(update != null )
{
update.FIRST_NAME = model.FIRST_NAME;
update.LAST_NAME = model.LAST_NAME;
update.GENDER = model.GENDER;
update.DOB = model.DOB;
//below line of code is very important.
db.B_MEMBER_REGISTER.Attach(update);
db.Entry(update).State = EntityState.Modified;
int resultcount = db.SaveChanges();
if (resultcount > 0)
{
response.MEMBER_ID = update.MEMBER_ID;
response.ResultCode = 0;
response.Message = "Updated Successfully";
}
}
}