asp.net mvc 4 - Copy one form Data to another form Entity Framework -

in mvc4 web application have copy data of 1 form have been saved newly created form. when copy data using following code, data moves 1 form , data previous form deleted. please specify why happening , how copy data.

  public formentity copyformdata(copyform copyform)     {         using (sipsentities db = new sipsentities())         {              if (db.qmsevaluationforms.where(x => x.isactive == true).any(x => x.formname == copyform.formname))             {                 throw new exception("form name exists!");             }             else             {                 var copydata = (from log in db.qmsevaluationforms                                 log.evaluationformid == copyform.copyfrom && log.isactive == true                                 select new                                 {                                     zeroonfatal = log.makescorezeroonfatal,                                     formcontrols = (from log1 in log.qmsevaluationformcontrols log1.isactive == true select log1).tolist(),                                     formparameters = (from log1 in log.qmsevaluationparameters log1.isactive == true select log1).tolist()                                 }).firstordefault();                  //insert new form                  qmsevaluationform newform = new qmsevaluationform();                 newform.formname = copyform.formname;                 newform.makescorezeroonfatal = copydata.zeroonfatal;                 newform.isactive = true;                 newform.createdon = datetime.now;                 newform.subprocessid = copyform.subprocessid;                  //(copy data child table) data deleted previous form , copied form                 newform.qmsevaluationformcontrols = copydata.formcontrols;                  //(copy data child table) data deleted previous form , copied form                 newform.qmsevaluationparameters = copydata.formparameters;                 db.qmsevaluationforms.add(newform);                 db.savechanges();                 return new formentity { formid = newform.evaluationformid, formname = newform.formname, makezero = newform.makescorezeroonfatal };               }           }     } 

i got solution of problem debugging code many times. happening here when copy child table data new form at

newform.qmsevaluationformcontrols = copydata.formcontrols;  

and newform.qmsevaluationparameters = copydata.formparameters;

the foreign key of each row changed new form's primary key. when copying data following method, every thing working fine-

  public formentity copyformdata(copyform copyform)     {         using (sipsentities db = new sipsentities())         {              if (db.qmsevaluationforms.where(x => x.isactive == true).any(x => x.formname == copyform.formname))             {                 throw new exception("form name exists!");             }             else             {                  var copydata = (from log in db.qmsevaluationforms                                  log.evaluationformid == copyform.copyfrom && log.isactive == true                                  select log).firstordefault();                 //insert new form                 list<qmsevaluationformcontrol> cloneformcontrollist = (from log1 in copydata.qmsevaluationformcontrols log1.isactive==true select log1).tolist();                 list<qmsevaluationparameter> clonepaameterlist = (from log1 in copydata.qmsevaluationparameters log1.isactive == true select log1).tolist();                 qmsevaluationform newform = new qmsevaluationform();                 newform.formname = copyform.formname;                 newform.makescorezeroonfatal = copydata.makescorezeroonfatal;                 newform.isactive = true;                 newform.createdon = datetime.now;                 newform.subprocessid = copyform.subprocessid;                foreach(var control in cloneformcontrollist){                    qmsevaluationformcontrol controldata=new qmsevaluationformcontrol();                    controldata.caption=control.caption;                    controldata.createdon=datetime.now;                    controldata.fieldtypeid=control.fieldtypeid;                    controldata.formvalidationparameterid=control.formvalidationparameterid;                    controldata.listnameid=control.listnameid;                    controldata.ismandatory=control.ismandatory;                    controldata.maxsize=control.maxsize;                    controldata.isactive=control.isactive;                    newform.qmsevaluationformcontrols.add(controldata);                 }                 foreach (var parameter in clonepaameterlist)                {                    qmsevaluationparameter parameterdata = new qmsevaluationparameter();                    parameterdata.category = parameter.category;                    parameterdata.parameteercode = parameter.parameteercode;                    parameterdata.evaluationparameter = parameter.evaluationparameter;                    parameterdata.listnameid = parameter.listnameid;                    parameterdata.criticaltypeid = parameter.criticaltypeid;                    parameterdata.weightage = parameter.weightage;                    parameterdata.isactive = parameter.isactive;                    parameterdata.createdon = datetime.now;                    newform.qmsevaluationparameters.add(parameterdata);                }                 db.qmsevaluationforms.add(newform);                 db.savechanges();                 return new formentity { formid = newform.evaluationformid, formname = newform.formname, makezero = newform.makescorezeroonfatal };               }           }     }