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--构造测试数据: 只作演示用
CREATE TABLE [dbo].[Tim_LinqTable](
[Id] int PRIMARY KEY IDENTITY(1,1) NOT NULL,
[Name] [varchar](50) NOT NULL,
[Parent] int NOT NULL,
)
GO
INSERT INTO [Tim_LinqTable]
SELECT 'A',0 UNION ALL
SELECT 'A1',1 UNION ALL
SELECT 'A2',1 UNION ALL
SELECT 'B1',2 UNION ALL
SELECT 'B2',3 UNION ALL
SELECT 'C1',4 UNION ALL
SELECT 'C2',4 UNION ALL
SELECT 'D1',5 UNION ALL
SELECT 'D2',5 UNION ALL
SELECT 'D3',5
GO
WITH temp
AS
(
SELECT * FROM [Tim_LinqTable] WHERE Parent = 3
UNION ALL
SELECT m.* FROM [Tim_LinqTable] AS m
INNER JOIN temp AS child ON m.Parent = child.Id
)
SELECT * FROM temp
GO
--查询 Parent=3 的所有子数据结果如下:
Id Name Parent
----------- -------------------------------------------------- -----------
5 B2 3
8 D1 5
9 D2 5
10 D3 5
(4 row(s) affected)
//好,下边来看看用C#怎么实现上边的SQL语句吧:
void Main()
{
var query=GetClassID(3);
Console.WriteLine("Id\tName\tParent");
query.ToList().ForEach(q=>Console.WriteLine("{0}\t{1}\t{2}",q.Id,q.Name,q.Parent));
/*
Id Name Parent
5 B2 3
8 D1 5
9 D2 5
10 D3 5
*/
}
public IEnumerable<Tim_LinqTable> GetClassID(int p_id)
{
var query = from c in this.Tim_LinqTables
where c.Parent == p_id
select c;
return query.ToList().Concat(query.ToList().SelectMany(t => GetClassID(t.Id)));
}
/// <summary>
/// 对于可以树型化的数据进行树型化
/// </summary>
/// <typeparam name="T">需要树型化的数据类名</typeparam>
/// <param name="collection">顶级树形集合</param>
/// <param name="action">项处理过程</param>
/// <param name="func">次级栏目获取方法</param>
/// <param name="depth">深度,默认从0开始</param>
public void CTree(IQueryable<T> collection, Action<T, int> action, Func<T, IQueryable<T>> func, int depth = 1)
{
foreach (var t in collection)
{
action(t, depth);
var list = func(t);
CTree(list, action, func, depth + 1);
}
}
#endregion