根据您的描述，我建议您可以尝试使用下面的linq。
班级：

[Table("ProductionLibrary")]
public partial class ProductionLibrary
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    public int ProductionPlanBatchId { get; set; }
    public int? ProcessingQuantity { get; set; }
}
[Table("ProductionPlan")]
public partial class ProductionPlan
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    public int ProductionPlanNo { get; set; }
    [StringLength(10)]
    public string ProductConfigName { get; set; }
    public int? Quantity { get; set; }
    [StringLength(10)]
    public string ExecState { get; set; }
    [StringLength(10)]
    public string ProcessingCompletionDate { get; set; }
    public int? ProductionPlanId { get; set; }
}
public partial class ProductionPlan_Batch
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    public int ProductionPlanBatchId { get; set; }
    public int? ProductionPlanId { get; set; }
}

林克：

var re = from a in dbcontext.ProductionPlans
                  from b in dbcontext.ProductionPlan_Batch
                  from c in dbcontext.ProductionLibraries
                  where a.ProductionPlanId == b.ProductionPlanId 
                  && b.ProductionPlanBatchId == c.ProductionPlanBatchId
                  && a.ExecState != "Deleted" 
                  select new
                  {
                      a.ExecState,
                      a.ProcessingCompletionDate,
                      a.ProductConfigName,
                      a.ProductionPlanId,
                      a.ProductionPlanNo,
                      a.Quantity,
                      b.ProductionPlanBatchId,
                      bProductionPlanId = b.ProductionPlanId,
                      c.ProcessingQuantity,
                      cProductionPlanId = c.ProductionPlanBatchId
                  }
                  into p
                  group p by new { 
                      p.ProductionPlanId, 
                      p.ProductionPlanNo , 
                      p.ProductConfigName,
                      p.ProcessingCompletionDate,
                      p.ExecState,
                      p.ProductionPlanBatchId
                  } into grpre
                  where Math.Round(((decimal)grpre.Sum(x => x.ProcessingQuantity))/((decimal)grpre.Sum(x => x.Quantity)), 2) <1
                  orderby grpre.Key.ProductionPlanBatchId descending
                  select new {
                      grpre.Key.ProductionPlanBatchId,
                      grpre.Key.ProductionPlanNo,
                      grpre.Key.ProductConfigName,
                      ProcessingQuantity = grpre.Sum(x =>x.ProcessingQuantity) ,
                      Quantity = grpre.Sum(x => x.Quantity),
                      grpre.Key.ExecState,
                      Percent = Math.Round(((decimal)grpre.Sum(x => x.ProcessingQuantity)) / ((decimal)grpre.Sum(x => x.Quantity)), 2),
                      grpre.Key.ProcessingCompletionDate
                  };