字符串的“sum”与linq中的“，”分隔为实体

Question

我需要查询Linq to Entities，结果是一个unic字符串与“，”分隔。 我尝试使用Cont = String.Join(", ", op.OperacionesContenedores.Select(Function(jj) jj.Id.ToString).ToArray())

示例：

(From op In dContext.Operaciones
Join opTr In dContext.OperacionesTransito On opTr.idOperacion Equals op.id
 Group Join opTrContenedor In dContext.OperacionesContenedores On opTr.idOperacion Equals opTrContenedor.IdOperacion Into grpOpTrContenedor = Group
From opTrContenedor In grpOpTrContenedor.DefaultIfEmpty()
Select New With {.idOperacion = op.id,
.Expediente = op.ReferenciaEmpresaResponsable,
.ReferenciaCliente = op.ReferenciaEmpresaCliente,                                            
.Cont = String.Join(", ", op.OperacionesContenedores.Select(Function(jj) jj.Id.ToString).ToArray())
}).Distinct().AsQueryable

这应该返回“Expediente”，“referenciaCliente”，“con1，cont2，cont3”，但在查询执行时会产生错误：

LINQ to Entities does not recognize the method 'System.String Join(System.String, System.String[])' method, and this method cannot be translated into a store expression。