sql server - context.SaveChanges() not persisting data in database -

im working on mvc app.

when call context.savechanges update specific records. update not registered in database. not runtime error either. in notice records not updated. still see same values. insert functionality work perfectly.

enter code here  public admission update(int stuid){          vddata.vidyadaanentities context = new vddata.vidyadaanentities();         vddata.student_master studentmaster = new vddata.student_master();          studentmaster.student_id = stuid;         studentmaster.student_first_name = this.firstname;         studentmaster.student_middle_name = this.middlename;         studentmaster.student_last_name = this.lastname;         studentmaster.student_address_1 = this.address;         studentmaster.student_address_2 = this.address2;         studentmaster.student_city = this.city;         studentmaster.student_state = this.state;         studentmaster.student_pin_code = this.pincode;         context.savechanges(); // here wont give kind of error. runs sucessfully. } 

it seems want update, code should

vddata.student_master studentmaster = context.student_masters.single(p=>p.student_id == stuid); 

and should not change student_id if primary key.

public admission update(int stuid){          vddata.vidyadaanentities context = new vddata.vidyadaanentities();         //vddata.student_master studentmaster = new vddata.student_master(); //replace vddata.student_master studentmaster = context.student_masters.where(p=>p.student_id == stuid);          studentmaster.student_id = stuid;         studentmaster.student_first_name = this.firstname;         studentmaster.student_middle_name = this.middlename;         studentmaster.student_last_name = this.lastname;         studentmaster.student_address_1 = this.address;         studentmaster.student_address_2 = this.address2;         studentmaster.student_city = this.city;         studentmaster.student_state = this.state;         studentmaster.student_pin_code = this.pincode;         context.savechanges();