C# 如何过滤数据表？
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How I can filter a Datatable?
提问by Tarasov
I use a DataTable with Information about Users and I want search a user or a list of users in this DataTable. I try it butit don't work :(
我使用带有用户信息的数据表，我想在此数据表中搜索用户或用户列表。我试过了，但它不起作用:(
Here is my c# code:
这是我的 C# 代码：
public DataTable GetEntriesBySearch(string username,string location,DataTable table)
{
list = null;
list = table;
string expression;
string sortOrder;
expression = "Nachname = 'test'";
sortOrder = "nachname DESC";
DataRow[] rows = list.Select(expression, sortOrder);
list = null; // for testing
list = new DataTable(); // for testing
foreach (DataRow row in rows)
{
list.ImportRow(row);
}
return list;
}
采纳答案by Kadir
You can use DataView.
您可以使用数据视图。
DataView dv = new DataView(yourDatatable);
dv.RowFilter = "query"; // query example = "id = 10"
回答by Maxim Kornilov
It is better to use DataView for this task.
最好将 DataView 用于此任务。
Example of the using it you can find in this post: How to filter data in dataview
您可以在这篇文章中找到使用它的示例：How to filter data in dataview
回答by Tim Schmelter
If you're using at least .NET 3.5, i would suggest to use Linq-To-DataTableinstead since it's much more readable and powerful:
如果您至少使用 .NET 3.5，我建议Linq-To-DataTable改用它，因为它更具可读性和功能：
DataTable tblFiltered = table.AsEnumerable()
.Where(row => row.Field<String>("Nachname") == username
&& row.Field<String>("Ort") == location)
.OrderByDescending(row => row.Field<String>("Nachname"))
.CopyToDataTable();
Above code is just an example, actually you have many more methods available.
上面的代码只是一个例子，实际上你有更多的方法可用。
Remember to add using System.Linq;and for the AsEnumerableextension method a reference to the System.Data.DataSetExtensionsdll (How).
请记住using System.Linq;为AsEnumerable扩展方法添加对System.Data.DataSetExtensionsdll的引用（How）。
回答by VolkanCetinkaya
clear:
清除：
list = null; // for testing
list = new DataTable(); // for testing
foreach (DataRow row in rows)
{
list.ImportRow(row);
}
use:
用：
.CopyToDataTable()
example:
例子：
string _sqlWhere = "Nachname = 'test'";
string _sqlOrder = "Nachname DESC";
DataTable _newDataTable = yurDateTable.Select(_sqlWhere, _sqlOrder).CopyToDataTable();
回答by nghiavt
For anybody who work in VB.NET (just in case)
对于在 VB.NET 中工作的任何人（以防万一）
Dim dv As DataView = yourDatatable.DefaultView
dv.RowFilter ="query" ' ex: "parentid = 0"
回答by Santosh Kumar
Hi we can use ToLower Method sometimes it is not filter.
嗨，我们可以使用 ToLower 方法，有时它不是过滤器。
EmployeeId = Session["EmployeeID"].ToString();
var rows = dtCrewList.AsEnumerable().Where
(row => row.Field<string>("EmployeeId").ToLower()== EmployeeId.ToLower());
if (rows.Any())
{
tblFiltered = rows.CopyToDataTable<DataRow>();
}
回答by Dilaksha A
Sometimes you actually want to return a DataTablethan a DataView. So a DataViewwas not good in my case and I guess few others would want that too. Here is what I used to do
有时您实际上想要返回 a DataTablethan a DataView。所以 aDataView对我来说不好，我想很少有人也会想要它。这是我以前做的
myDataTable.select("myquery").CopyToDataTable()
This will filter myDataTablewhich is a DataTable and return a new DataTable
这将过滤myDataTable哪个是 DataTable 并返回一个新的DataTable
Hope someone will find that is useful
希望有人会发现这是有用的
