Entity Framework Learning VI: Some common query techniques

var people == = ==== = = = = = = = =new{p. Lastname,p.firstname,p.persontype.typename}); foreach (var in people) {Console.WriteLine ("{0} {1} {2}"  , person. FirstName, person. LastName, person. TypeName);}

 var  people = context. People.where (P  = p.personstate == personstate.active). (P  => P.lastname). ThenBy (P  => P.firstname). Select (P  = new  {p.lastname,p. Firstname,p.persontype.typename});  foreach  (var  person in   people) {Console.WriteLine (  {0} {1} {2}   " ,person. FirstName, person. LastName, person. TypeName);}  

var explicitquery = from in context. Peoplewhere oneperson.personstate = = personstate.active;

 Public classpersoninfo{ Public intPersonId {Get;Set; } Public stringPersonType {Get;Set; } Public stringFirstName {Get;Set; } Public stringLastName {Get;Set; }}

varExplicitquery = fromOnepersoninchcontext. PeoplewhereOneperson.personstate = =personstate.active byOneperson.lastname, Oneperson.firstnameSelect NewPersoninfo{lastname=Oneperson.lastname,firstname=Oneperson.firstname,persontype=Oneperson.persontype.typename,personid=Oneperson.personid,phones= OnePerson.Phones.Select (ph=>Ph. PhoneNumber)};foreach(varPersoninchexplicitquery) {Console.WriteLine ("{0} {1} {2} {3}", person. FirstName, person. Lastname,person. PersonType, person. PERSONID);foreach(varPhoneinchPerson . Phones) {Console.WriteLine (" "+phone);}}

Min

var min = context. People.min (p = p.birthdate);

Count

var min = context. People.min (p = p.birthdate);

 var  query = from  Oneperson in   context. People  where  oneperson.personstate == select  new  Span style= "color: #000000;" >{oneperson.heightinfeet,oneperson.personid};query  = query. (P => P.heightinfeet);  var  sum = query. Sum (P => P.heightinfeet); Console.WriteLine (sum);  

 var  query = from  Oneperson in   context. People  where  oneperson.personstate == select  new  Span style= "color: #000000;" >{oneperson.heightinfeet,oneperson.personid};query  = query. (P => P.heightinfeet);  var  sum = query. Sum (P => P.heightinfeet); Console.WriteLine (sum);  

 from inch context. Peoplewhere2) >new DateTime (1970,1,1) Select New {Oneperson.heightinfeet,oneperson.personid};

Paging:

var people ===1) * criteria. PageSize). Take (criteria. PageSize);

Using join:

 var  people = from  person in   context. Peoplejoin persontype   context. Persontypeson person. Persontypeid equals Persontype.persontypeid  select  new  { var  people = from  person in   context. Peoplejoin persontype   context. Persontypeson person. Persontypeid equals Persontype.persontypeid  select  new  { 

People == = = ==new= =new{p. Person.lastname,p.person.firstname,p.persontype.typename});

Grouping and left connections:

 from  Oneperson in   context. Peoplegroup Oneperson by  new   select  new  {month  = MonthGroup.Key.Month, Count  = Monthgroup.count ()};  

 var  methodquery =context. People.groupby (Oneperson  = new   => Monthgroup). Select (Monthgroup  = new  {month  = Monthgroup.key.month,count  = 

 from  person in   context. Peoplejoin persontype   context. Persontypeson person. Persontypeid Equalspersontype.persontypeid into Finalgroup  from  Groupeddata in   Finalgroup.defaultifempty ()  select  new  {person. Lastname,person. Firstname,typename  = groupeddata.typename??  " unknown   " };  

 var  methodquery = context. People.groupjoin (context. Persontypes,person  => person. Persontypeid,persontype  => Persontype.persontypeid, (person, type)  = > new  {person  =  Person,persontype  = type}). SelectMany (groupeddata  =>groupeddata.persontype.defaultifempty (), (group , persontype)  = new  {group. Person.lastname,group. Person.firstname,typename  = persontype.typename??  " unknown   "  

 from  Oneperson in   context. People  from  onephone in   Oneperson.phones  orderby   Oneperson.lastname, Onephone.phonenumber  select  new  {oneperson.lastname,oneperson.firstname,onephone.phonenumber};  

var methodquery == = person. Phones, (person, phone) =new== p.phonenumber);

Distinct

var uniquequery == = = p.persontype.typename). Distinct ();

Union:

 var  unionquery = context. People.select (P  = new  {name  = P.lastname +  "  + P.firstname,rowtype  =  person  Span style= "color: #800000;" > " }). Union (Context.Companies.Select (c  = new  {name  = C.companyname,rowtype  = "  company    => result. RowType). ThenBy (Result  = = result. Name); 

Entity Framework Learning VI: Some common query technologies