linq - 使用 linq 保存新记录或更新现有记录

Question

这是我用linq保存记录的方式:(我的Q在下面)

    public void SaveEmployee(Employee employee)
    {

        using (BizNetDB db = new BizNetDB())
        {
            BizNet.SqlRep.Data.Employee oldEmployee = (from e in db.Employees
                                                       where e.EmployeeID == employee.EmployeeID
                                                   select e).SingleOrDefault();
            if (oldEmployee == null)
            {
                oldEmployee = new BizNet.SqlRep.Data.Employee();
                oldEmployee.BirthDate = employee.BirthDate;
                oldEmployee.WorkRole = employee.WorkRole;
                oldEmployee.CurrentFlag = employee.CurrentFlag;
                oldEmployee.HireDate = employee.HireDate;
                ...
                db.Employees.InsertOnSubmit(oldEmployee);
            }
            else
            {
                if (oldEmployee.BirthDate.Date != employee.BirthDate.Date)
                    oldEmployee.BirthDate = employee.BirthDate;
                if (oldEmployee.CurrentFlag != employee.CurrentFlag)
                    oldEmployee.CurrentFlag = employee.CurrentFlag;
                if (oldEmployee.HireDate.Date != employee.HireDate.Date)
                    oldEmployee.HireDate = employee.HireDate;
            }

            oldEmployee.ModifiedDate = DateTime.Now;
            db.SubmitChanges();
            employee.EmployeeID = oldEmployee.EmployeeID;
        }
    }

我的问题是:

一个。 if 语句是必要的吗？为什么不在没有的情况下进行分配 查看？ mybe if block 需要更多的 cpu ..

为什么要把新记录 block 和更新 block 分开？

当记录是新的时候它会做

db.Employees.InsertOnSubmit(oldEmployee);

然后继续更新例程...

Answer 1

您这样做的方式需要 if 语句的唯一原因是新建并插入它，因此我会为此使用 if 语句。

我会这样做:

 public void SaveEmployee(Employee employee)
{
    using (BizNetDB db = new BizNetDB())
    {
        BizNet.SqlRep.Data.Employee oldEmployee = 
                    (from e in db.Employees
                    where e.EmployeeID == employee.EmployeeID
                    select e).SingleOrDefault();

        if (oldEmployee == null)
        {
            oldEmployee = new BizNet.SqlRep.Data.Employee();
            db.Employees.InsertOnSubmit(oldEmployee);
        }

        if (oldEmployee.BirthDate.Date != employee.BirthDate.Date)
            oldEmployee.BirthDate = employee.BirthDate;
        if (oldEmployee.CurrentFlag != employee.CurrentFlag)
            oldEmployee.CurrentFlag = employee.CurrentFlag;
        if (oldEmployee.HireDate.Date != employee.HireDate.Date)
            oldEmployee.HireDate = employee.HireDate;

        oldEmployee.ModifiedDate = DateTime.Now;
        db.SubmitChanges();
        employee.EmployeeID = oldEmployee.EmployeeID;
    }
}

我还认为有一种方法可以将一个对象的属性映射到另一个对象，但目前我没有想到。无论如何，它可能对您尝试做的事情不起作用，因为您似乎稍后会使用 ModifiedDate 和 EmployeeID 做一些其他事情。