使用linq保存新记录或更新存在记录

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.是if语句nesccery？为什么不在没有支票的情况下进行分配呢？mybe if if block需要更多cpu ..

湾 为什么要翻新新记录块和更新块？

当记录是新的时,它会做

db.Employees.InsertOnSubmit(oldEmployee);

然后继续更新例程......

Answer 1

你这样做的方式是你需要if语句的唯一原因是新建它并插入它,所以我会使用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;
    }
}

我也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的属性,但此刻它让我感到惊讶.它可能无法用于你想要做的事情,因为看起来你以后用ModifiedDate和EmployeeID做了一些其他事情.