InvalidOperationException:Sequence包含多个元素

Question

我有以下代码用于工资单程序.第一个字典保存在主数据表中保存的员工ID和相应的基本工资.第二个字典保存员工ID和相应的基本工资,用于工资配件表 - 用于处理.我想更新主表中不匹配的每个员工ID的工资补贴基本工资.(工资变动).

var OHEMDictionary = employees.OrderBy(es => es.empID)
                     .ToDictionary(od => od.empID,
                     od => od.salary);

var SalaryFitmentDictionary = salaryFitments
                              .Where(x => x.U_PD_Code.Trim().ToString() == "SYS001")
                              .OrderBy(es => es.U_Employee_ID)
                              .ToDictionary(od => od.U_Employee_ID,
                                            od => od.U_PD_Amount);

var difference = OHEMDictionary
                .Where(kv => SalaryFitmentDictionary[kv.Key] != kv.Value);

difference.ToList().ForEach(x =>
                    {
                        decimal salary = x.Value.Value;

                        var codeToUpdate = salaryFitments
                                        .Where(y => y.U_Employee_ID.Equals(x.Key))
                                        .Select(z => z.Code)
                                        .SingleOrDefault(); `**<---exception thrown here**`

                        var salaryFitment = salaryFitmentService
                                            .GetSalaryFitment(codeToUpdate);

                        if (salaryFitment != null)
                        {
                            // Save record
                            salaryFitmentService
                           .UpdateSalaryFitment(salaryFitment, salary.ToString());
                        }
                    });

但是,我一直在收到错误'Sequence contains more than one element'.我该如何解决这个错误？

Answer 1

您可以使用FirstOrDefault(),但如果存在多个元素,SingleOrDefault会抛出异常.

在这里,您可以确切地看到单个或默认方法的作用:http: //msdn.microsoft.com/en-us/library/system.linq.enumerable.singleordefault(v=vs.100).aspx