LINQ到实体选择查询错误

本文关键字：查询 错误 选择 实体 LINQ | 更新日期: 2023-09-27 17:52:39

using (SmartEntities employeeverificationcontext = new SmartEntities())
{
    Employee emp = (from c in employeeverificationcontext.EmployeeEntity 
                    where c.Employee_ID == emp_detail.EmployeeID 
                    select new Employee {c.Status}).FirstOrDefault();
    emp.Status = emp_detail.Status;
    int i=employeeverificationcontext.SaveChanges();
    if (i > 0)
    {
        result = "Verification Process Completed";
    }
}

error: error 1 Cannot initialize type 'SmartWCF。因为它没有实现'System.Collections.IEnumerable'**

LINQ到实体选择查询错误

应该选择当前对象(c)而不是select new Employee {c.Status}

所以你的查询应该是:

Employee emp = (from c in employeeverificationcontext.EmployeeEntity 
               where c.Employee_ID == emp_detail.EmployeeID 
               select c).FirstOrDefault();

或

Employee emp = employeeverificationcontext.EmployeeEntity
                      .FirstOrDefault(c=> Employee_ID == emp_detail.EmployeeID);

只选择Status是这样做的:

var employeeStatus = (from c in employeeverificationcontext.EmployeeEntity 
                        where c.Employee_ID == emp_detail.EmployeeID 
                      select c.Status).FirstOrDefault();

但是，如果您想将其设置为新状态并将其保存到数据上下文中，这将无法帮助您。在这种情况下，您必须选择Employee。

这篇文章中提到了一些替代方案:如何在LINQ中更新单列而不加载整行?

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