Question

我有两个列表

    List A                         List B
    ID  FirstName  DepartmentID    ID  FirstName  DepartmentID
    5   Peter      Null            5   Peter      1 
    9   Steve      Null            9   Steve      2
    16  Mark       Null            16  Mark       3

我想使用LINQ比较这些列表，如果两个列表中的ID相等，我想在第一个列表中设置DepartmentID，列表。

提前谢谢。

Answer 1

ListA.ForEach(a=>a.DepartmentID = ListB.Any(b=>b.ID == a.ID) ? ListB.First(b=>b.ID == a.ID).DepartmentID : null);

编辑：如果要检查null。

Answer 2

你可以加入他们。然后枚举结果并保存更改：

var results = from a in ListA
              join b in ListB on ai.ID equals bi.ID
              select new
              {
                  itemA = a,
                  itemB = b
              };

foreach(var result in results)
{
    // This was not listed as a requirement, but it may be a valid check
    if (itemA.FirstName == itemB.FirstName)
    {
        itemB.DepartmentID = itemA.DepartmentID;
    }
}

DataContext.SubmitChanges();

Answer 3

ListA.Join(ListB, x => x.ID, y => y.ID, (x, y) =>
{
    x.DepartmentID = y.DepartmentID;
    return 0;
}).ToArray();

Answer 4

您可以使用其他列表并使用以下代码

var temp = from ai in ListA 
        join bi in ListB on ai.id equals bi.id
        select bi;

var ListC = temp.ToList();

Answer 5

var replacements = ListA
    .Where(a => a.DepartmentID == null)
    .Join(ListB, 
         a => a.ID, 
         b => b.ID, 
         (a, b) => new { Source = a, Replacement = b }
    );

foreach (var item in replacements)
{
    // here you could perform more replacements
    item.Source.DepartmentID = item.Replacement.DepartmentID;
}

如何比较两个列表并将值设置为列表属性

5 个答案: