c# - 将数据从 Linq to SQL 查询返回为自定义数据类型

Question

我在 linq 中编写了一个查询，根据雇员编号返回 10 名不同雇员的信息。虽然我是 linq 的新手，但我在返回时遇到了问题。我在这段代码中做错了什么？

 public class queryClass
    {
        private string firstName { get; set; }
        private string lastName { get; set; }
        private int employeeNo { get; set; }
        private string department { get; set; }
    }

    public static queryClass[] GetEmpData(int empID1, int empID2, int empID3, int empID4, int empID5, int empID6, int empID7, int empID8, int empID9, int empID10)
    {

        using(var context = new EmpInfoDataContext())
        {
            var query = from e in context.EmployeTable
                        join j in context.JobTitles on e.JobTitle equals j.JobTitle
                        where e.EmployeeNo == empID1
                        where e.EmployeeNo == empID2
                        where e.EmployeeNo == empID3
                        where e.EmployeeNo == empID4
                        where e.EmployeeNo == empID5
                        where e.EmployeeNo == empID6
                        where e.EmployeeNo == empID7
                        where e.EmployeeNo == empID8
                        where e.EmployeeNo == empID9
                        where e.EmployeeNo == empID10
                        select new  {e.FirstName, e.LastName, e.EmployeeNo, j.Department};

            return query.ToArray();
        }
    }

在“return query.Toarray();”下，错误是“无法将表达式类型 '{FirstName:string, LastName:string, EmployeeNo:int, Department:string}[] 转换为返回类型 'Employeephotos.Models。 HomeModel.queryClass[]"

感谢您提供的任何帮助。

Answer 1

您的 where 子句应该是单个 bool 表达式。

where e.EmployeeNo == empID1 || e.EmployeeNo == empID2 ... etc

并确保声明所选项目的类型

select new queryClass {
    firstName = e.FirstName,
    lastName = e.LastName,
    employeeNo = e.EmployeeNo,
    department = j.Department
};