LINQ Usage Notes

How do I use Between...and in LINQ?

var  from inch context. Parent            from in context. Child.where (x = P.cob >= x.effective)                                   = P.cob <= x.expiry)                                   . DefaultIfEmpty ()            group p by P.cob into PG            Selectnew            {              = pg. Key,              = pg. Count ()            };

The following is a multiple where condition to handle the Between...and, but an inner join.

var  from inch Appointments                          from inch Properties                          from inch Clients                         where a.id = =                        p.oidwhere a.start.date >=                        startdate.date where a.start.date<=enddate.date

How to use in?

varAllowedstatus =New[]{"A","B","C" };varfilteredorders = orders. Order.where (o =allowedstatus.contains (O.statuscode));
orinchquery Syntax:varFilteredorders = fromOrderinchorders. OrderwhereAllowedstatus. Contains (Order. StatusCode)SelectOrder

How to use multiple connection conditions Join...on?

varquery = fromObj_iinchSet1join Obj_jinchSet2 onNew{JoinProperty1=Obj_i.somefield1, JoinProperty2=Obj_i.somefield2, JoinProperty3=obj_i.somefield3, JoinProperty4=obj_i.somefield4} equalsNew{JoinProperty1=Obj_j.someotherfield1, JoinProperty2=Obj_j.someotherfield2, JoinProperty3=obj_j.someotherfield3, JoinProperty4=Obj_j.someotherfield4}
Http://stackoverflow.com/questions/3020442/linq-joining-in-c-sharp-with-multiple-conditions

If you want to achieve the effect of this SQL:

SELECT *  from table1 a  Left JOIN  on =  and  = and <= and = 0 ;

Can do this:

varquery = ( fromXinchcontext.table1 Join yinchContext.table2 onNew{Key1=X.col1, Key2=x.col2 Key3=true, Key4=true} equals {Key1=B.key1, Key2=B.key2, Key3= b.from_date<DateTime.Now, Key4= !b.deleted} into result fromRinchresult. DefaultIfEmpty ()Select New{x.something, r.something}
Http://stackoverflow.com/questions/7765230/linq-to-entity-multiple-join-conditions

How to use group ... by group?

such as SQL:

SELECT *  from < TableName>GROUPby<Column1>,<Column2> 

Group  by  = = new {x.column1, x.column2})

var query = ( from in transactions             new  {t.materialid, T.productid } into             grp                    Selectnew                    {                        grp. Key.materialid,                        Grp. Key.productid,                        = grp. Sum (t = = t.quantity)                    }). ToList ();

LINQ Usage Notes