Entity Framework public class

 Public Abstract classBaseservice<t>whereT:class{    Private Static ReadOnlyDatabasecontext db =NewDatabasecontext ();  Public StaticT Add (t entity) {db. Entry<T> (entity). State =entitystate.added; Db.        SaveChanges (); returnentity; }     Public Static intCount (Expression<func<t,BOOL>>predicate) {        returnDb. Set<t>().    Count (predicate); }     Public Static BOOLUpdate (T entity) {db. Set<T>().        Attach (entity); Db. Entry<T> (entity). State =entitystate.modified; returnDb. SaveChanges () >0; }     Public Static BOOLDelete (T entiry) {db. Set<T>().        Attach (Entiry); Db. Entry<T> (Entiry). State =entitystate.deleted; returnDb. SaveChanges () >0; }     Public Static BOOLExist (Expression<func<t,BOOL>>predicate) {        returnDb. Set<t>().    any (predicate); }     Public StaticT Find (Expression<func<t,BOOL>>predicate) {        returnDb. Set<t>().    FirstOrDefault (predicate); }     Public StaticIqueryable<t> Findlist (Expression<func<t,BOOL>> predicate,intPageIndex,intPageSize,intTotalparamsorderfieldmodel[] orderbyexpression) {        varquery = db. Set<t>().        Where (predicate); varparameter = Expression.parameter (typeof(T),"o"); if(Orderbyexpression! =NULL&& orderbyexpression.length >0)        {            foreach(varOrderFieldinchorderbyexpression) {                varproperty =typeof(T).                GetProperty (Orderfield.propertyname); varPropertyaccess =expression.makememberaccess (parameter, property); varOrderbyexp =Expression.lambda (propertyaccess, parameter); stringOrdername = Orderfield.isdesc?"orderbydescending":" by"; Methodcallexpression Resultexp= Expression.call (typeof(queryable), Ordername,NewType[] {typeof(T), property. PropertyType}, query.                Expression, Expression.quote (orderbyexp)); Query= Query. Provider.createquery<t>(RESULTEXP); }        }        returnDb. Set<t>().    Where (predicate); }}

Entity Framework public class