使用 LINQ 从数据集中选择单列

发布于 2024-10-07 13:46:20 字数 451 浏览 0 评论 0原文

刚开始思考所有这些 LINQ 的东西，我似乎陷入了第一个障碍。

我有一个这样的数据表：

OrderNo     LetterGroup Filepath
----------- ----------- --------------------------------------------------
0           0           Letters/SampleImage.jpg
0           0           Letters/UKPC7_0.jpg
0           0           Letters/UKPC8_0.jpg

我需要的是将文件路径列中的所有文件路径获取到字符串数组中。我认为 LINQ 非常适合这个（我是对的吗？），但似乎无法构建正确的查询。

谁能提供一些代码示例来为我指明正确的方向？我已经四处寻找 - 但似乎一无所获。

原文

Just getting my head around all this LINQ stuff and it seems I'm stuck at the first hurdle.

I have a datatable as such:

OrderNo     LetterGroup Filepath
----------- ----------- --------------------------------------------------
0           0           Letters/SampleImage.jpg
0           0           Letters/UKPC7_0.jpg
0           0           Letters/UKPC8_0.jpg

What I need is to get all of the filepaths from the Filepath column into a String array. I thought LINQ would be perfect for this (am I right?), but can't seem to construct the correct query.

Can anyone provide some code samples that would point me in the right direction? I have searched around - but don't seem to be getting anywhere.

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第几種人 2024-10-14 13:46:20

有一些扩展方法可以使数据集的处理变得更加容易：

using System.Data.Linq;

var filePaths =
    from row in dataTable.AsEnumerable()
    select row.Field<string>("Filepath");

var filePathsArray = filePaths.ToArray();

您还可以使用方法语法将其放入一条语句中：

var filePaths = dataTable
    .AsEnumerable()
    .Select(row => row.Field<string>("Filepath"))
    .ToArray();

There are extension methods which make working with data sets much easier:

using System.Data.Linq;

var filePaths =
    from row in dataTable.AsEnumerable()
    select row.Field<string>("Filepath");

var filePathsArray = filePaths.ToArray();

You can also use the method syntax to put it in one statement:

var filePaths = dataTable
    .AsEnumerable()
    .Select(row => row.Field<string>("Filepath"))
    .ToArray();

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懒的傷心 2024-10-14 13:46:20

string[] filePaths = (from DataRow row in yourDataTable.Rows 
                     select row["Filepath"].ToString()).ToArray();

string[] filePaths = (from DataRow row in yourDataTable.Rows 
                     select row["Filepath"].ToString()).ToArray();

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吲‖鸣 2024-10-14 13:46:20

如果您想完全使用 LINQ，请设置数据库并创建上下文对象。那么您应该能够执行以下操作：

 var filepaths = from order in _context.Orders
                 select order.Filepath;

假设您的行表名为 Orders，我猜是您的订单的第一个列名称。如果您还想返回一组订单号以便稍后使用来了解文件路径的来源，您可以这样做：

var results = from order in _context.Orders
              select new
              {
                  order.OrderNo,
                  order.Filepath
              }

这将为您提供一个新的匿名类型，其中包含这两个值作为属性。

If you want to use LINQ all the way, set up your database and create a context object. Then you should be able to do something like this:

 var filepaths = from order in _context.Orders
                 select order.Filepath;

This is assuming your table for the row is named Orders, which I guess by your first column name of order. If you wanted to return a set of the order numbers as well for using later to know where the file path came from you could do something like so:

var results = from order in _context.Orders
              select new
              {
                  order.OrderNo,
                  order.Filepath
              }

This would give you a new anonymous type that contained both those values as properties.

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