DataTable.Select 方法

定义

获取 DataRow 对象数组。Gets an array of DataRow objects.

重载

Select()

获取由所有 DataRow 对象组成的数组。Gets an array of all DataRow objects.

Select(String)

获取由与筛选条件匹配的所有 DataRow 对象组成的数组。Gets an array of all DataRow objects that match the filter criteria.

Select(String, String)

以指定排序顺序,获取由与筛选条件匹配的所有 DataRow 对象组成的数组。Gets an array of all DataRow objects that match the filter criteria, in the specified sort order.

Select(String, String, DataViewRowState)

以与指定状态匹配的排序顺序,获取由与筛选条件匹配的所有 DataRow 对象组成的数组。Gets an array of all DataRow objects that match the filter in the order of the sort that match the specified state.

Select()

获取由所有 DataRow 对象组成的数组。Gets an array of all DataRow objects.

public:
 cli::array <System::Data::DataRow ^> ^ Select();
public System.Data.DataRow[] Select ();
member this.Select : unit -> System.Data.DataRow[]
Public Function Select () As DataRow()

返回

DataRow[]

一个 DataRow 对象数组。An array of DataRow objects.

示例

下面的示例 DataRow 通过方法返回对象的数组 SelectThe following example returns an array of DataRow objects through the Select method.

private void GetRows()
{
    // Get the DataTable of a DataSet.
    DataTable table = DataSet1.Tables["Suppliers"];
    DataRow[] rows = table.Select();

    // Print the value one column of each DataRow.
    for(int i = 0; i < rows.Length ; i++)
    {
        Console.WriteLine(rows[i]["CompanyName"]);
    }
}
Private Sub GetRows()
    ' Get the DataTable of a DataSet.
    Dim table As DataTable = DataSet1.Tables("Suppliers")
    Dim rows() As DataRow = table.Select()

    Dim i As Integer
    ' Print the value one column of each DataRow.
    For i = 0 to rows.GetUpperBound(0)
       Console.WriteLine(rows(i)("CompanyName"))
    Next i
End Sub

注解

若要确保正确的排序顺序,请用或指定排序条件 Select(String, String) Select(String, String, DataViewRowState)To ensure the proper sort order, specify sort criteria with Select(String, String) or Select(String, String, DataViewRowState).

另请参阅

适用于

Select(String)

获取由与筛选条件匹配的所有 DataRow 对象组成的数组。Gets an array of all DataRow objects that match the filter criteria.

public:
 cli::array <System::Data::DataRow ^> ^ Select(System::String ^ filterExpression);
public System.Data.DataRow[] Select (string? filterExpression);
public System.Data.DataRow[] Select (string filterExpression);
member this.Select : string -> System.Data.DataRow[]
Public Function Select (filterExpression As String) As DataRow()

参数

filterExpression
String

用于筛选行的条件。The criteria to use to filter the rows. 有关如何筛选行的示例,请参阅 DataView RowFilter 语法 [C#]For examples on how to filter rows, see DataView RowFilter Syntax [C#].

返回

DataRow[]

一个 DataRow 对象数组。An array of DataRow objects.

示例

下面的示例使用筛选表达式返回对象的数组 DataRowThe following example uses a filter expression to return an array of DataRow objects.

private void GetRowsByFilter()
{
    DataTable table = DataSet1.Tables["Orders"];
    // Presuming the DataTable has a column named Date.
    string expression;
    expression = "Date > #1/1/00#";
    DataRow[] foundRows;

    // Use the Select method to find all rows matching the filter.
    foundRows = table.Select(expression);

    // Print column 0 of each returned row.
    for(int i = 0; i < foundRows.Length; i ++)
    {
        Console.WriteLine(foundRows[i][0]);
    }
}
Private Sub GetRowsByFilter()
    
    Dim table As DataTable = DataSet1.Tables("Orders")

    ' Presuming the DataTable has a column named Date.
    Dim expression As String
    expression = "Date > #1/1/00#"
    Dim foundRows() As DataRow

    ' Use the Select method to find all rows matching the filter.
    foundRows = table.Select(expression)

    Dim i As Integer
    ' Print column 0 of each returned row.
    For i = 0 to foundRows.GetUpperBound(0)
       Console.WriteLine(foundRows(i)(0))
    Next i
End Sub

注解

若要创建 filterExpression 参数,请使用适用于 DataColumn 类的属性值的相同规则 Expression 来创建筛选器。To create the filterExpression argument, use the same rules that apply to the DataColumn class's Expression property value for creating filters.

若要确保正确的排序顺序,请用或指定排序条件 Select(String, String) Select(String, String, DataViewRowState)To ensure the proper sort order, specify sort criteria with Select(String, String) or Select(String, String, DataViewRowState).

如果筛选器中的列包含 null 值,则它将不是结果的一部分。If the column on the filter contains a null value, it will not be part of the result.

另请参阅

适用于

Select(String, String)

以指定排序顺序,获取由与筛选条件匹配的所有 DataRow 对象组成的数组。Gets an array of all DataRow objects that match the filter criteria, in the specified sort order.

public:
 cli::array <System::Data::DataRow ^> ^ Select(System::String ^ filterExpression, System::String ^ sort);
public System.Data.DataRow[] Select (string? filterExpression, string? sort);
public System.Data.DataRow[] Select (string filterExpression, string sort);
member this.Select : string * string -> System.Data.DataRow[]
Public Function Select (filterExpression As String, sort As String) As DataRow()

参数

filterExpression
String

用于筛选行的条件。The criteria to use to filter the rows. 有关如何筛选行的示例,请参阅 DataView RowFilter 语法 [C#]For examples on how to filter rows, see DataView RowFilter Syntax [C#].

sort
String

指定列和排序方向的字符串。A string specifying the column and sort direction.

返回

DataRow[]

由与筛选条件匹配的 DataRow 对象组成的数组。An array of DataRow objects matching the filter expression.

示例

下面的示例使用筛选表达式返回对象的数组 DataRowThe following example uses a filter expression to return an array of DataRow objects.

using System;
using System.Data;

public class A {

   public static void Main() {
      DataTable table = new DataTable("Orders");
      table.Columns.Add("OrderID", typeof(Int32));
      table.Columns.Add("OrderQuantity", typeof(Int32));
      table.Columns.Add("CompanyName", typeof(string));
      table.Columns.Add("Date", typeof(DateTime));

      DataRow newRow = table.NewRow();
      newRow["OrderID"] = 1;
      newRow["OrderQuantity"] = 3;
      newRow["CompanyName"] = "NewCompanyName";
      newRow["Date"] = "1979, 1, 31";

      // Add the row to the rows collection.
      table.Rows.Add(newRow);

      DataRow newRow2 = table.NewRow();
      newRow2["OrderID"] = 2;
      newRow2["OrderQuantity"] = 2;
      newRow2["CompanyName"] = "NewCompanyName1";
      table.Rows.Add(newRow2);

      DataRow newRow3 = table.NewRow();
      newRow3["OrderID"] = 3;
      newRow3["OrderQuantity"] = 2;
      newRow3["CompanyName"] = "NewCompanyName2";
      table.Rows.Add(newRow3);

      // Presuming the DataTable has a column named Date.
      string expression = "Date = '1/31/1979' or OrderID = 2";
      // string expression = "OrderQuantity = 2 and OrderID = 2";

      // Sort descending by column named CompanyName.
      string sortOrder = "CompanyName ASC";
      DataRow[] foundRows;

      // Use the Select method to find all rows matching the filter.
      foundRows = table.Select(expression, sortOrder);

      // Print column 0 of each returned row.
      for (int i = 0; i < foundRows.Length; i++)
         Console.WriteLine(foundRows[i][2]);
   }
}
Imports System.Data

Public Class A

   Public Shared Sub Main()
      Dim table As New DataTable("Orders")
      table.Columns.Add("OrderID", GetType(Int32))
      table.Columns.Add("OrderQuantity", GetType(Int32))
      table.Columns.Add("CompanyName", GetType(String))
      table.Columns.Add("Date", GetType(DateTime))

      Dim newRow As DataRow = table.NewRow()
      newRow("OrderID") = 1
      newRow("OrderQuantity") = 3
      newRow("CompanyName") = "NewCompanyName"
      newRow("Date") = "1979, 1, 31"

      ' Add the row to the rows collection.
      table.Rows.Add(newRow)

      Dim newRow2 As DataRow = table.NewRow()
      newRow2("OrderID") = 2
      newRow2("OrderQuantity") = 2
      newRow2("CompanyName") = "NewCompanyName1"
      table.Rows.Add(newRow2)

      Dim newRow3 As DataRow = table.NewRow()
      newRow3("OrderID") = 3
      newRow3("OrderQuantity") = 2
      newRow3("CompanyName") = "NewCompanyName2"
      table.Rows.Add(newRow3)

      ' Presuming the DataTable has a column named Date.
      Dim expression As String = "Date = '1/31/1979' or OrderID = 2"
      ' Dim expression As String = "OrderQuantity = 2 and OrderID = 2"

      ' Sort descending by column named CompanyName.
      Dim sortOrder As String = "CompanyName ASC"
      Dim foundRows As DataRow()

      ' Use the Select method to find all rows matching the filter.
      foundRows = table.[Select](expression, sortOrder)

      ' Print column 0 of each returned row.
      For i As Integer = 0 To foundRows.Length - 1
         Console.WriteLine(foundRows(i)(2))
      Next
   End Sub
End Class

注解

若要形成 filterExpression 参数,请使用与创建 DataColumn 类的属性值相同的规则 ExpressionTo form the filterExpression argument, use the same rules for creating the DataColumn class's Expression property value. Sort参数还使用相同的规则来创建类的 Expression 字符串。The Sort argument also uses the same rules for creating class's Expression strings.

如果筛选器中的列包含 null 值,则它将不是结果的一部分。If the column on the filter contains a null value, it will not be part of the result.

另请参阅

适用于

Select(String, String, DataViewRowState)

以与指定状态匹配的排序顺序,获取由与筛选条件匹配的所有 DataRow 对象组成的数组。Gets an array of all DataRow objects that match the filter in the order of the sort that match the specified state.

public:
 cli::array <System::Data::DataRow ^> ^ Select(System::String ^ filterExpression, System::String ^ sort, System::Data::DataViewRowState recordStates);
public System.Data.DataRow[] Select (string? filterExpression, string? sort, System.Data.DataViewRowState recordStates);
public System.Data.DataRow[] Select (string filterExpression, string sort, System.Data.DataViewRowState recordStates);
member this.Select : string * string * System.Data.DataViewRowState -> System.Data.DataRow[]
Public Function Select (filterExpression As String, sort As String, recordStates As DataViewRowState) As DataRow()

参数

filterExpression
String

用于筛选行的条件。The criteria to use to filter the rows. 有关如何筛选行的示例,请参阅 DataView RowFilter 语法 [C#]For examples on how to filter rows, see DataView RowFilter Syntax [C#].

sort
String

指定列和排序方向的字符串。A string specifying the column and sort direction.

recordStates
DataViewRowState

DataViewRowState 值之一。One of the DataViewRowState values.

返回

DataRow[]

一个 DataRow 对象数组。An array of DataRow objects.

示例

下面的示例使用筛选器表达式和记录状态返回对象的数组 DataRowThe following example uses a filter expression and record state to return an array of DataRow objects.

private static void GetRowsByFilter()
{
    DataTable customerTable = new DataTable("Customers");
    // Add columns
    customerTable.Columns.Add("id", typeof(int));
    customerTable.Columns.Add("name", typeof(string));

    // Set PrimaryKey
    customerTable.Columns[ "id" ].Unique = true;
    customerTable.PrimaryKey = new DataColumn[]
        { customerTable.Columns["id"] };

    // Add ten rows
    for(int id=1; id<=10; id++)
    {
        customerTable.Rows.Add(
            new object[] { id, string.Format("customer{0}", id) });
    }
    customerTable.AcceptChanges();

    // Add another ten rows
    for(int id=11; id<=20; id++)
    {
        customerTable.Rows.Add(
            new object[] { id, string.Format("customer{0}", id) });
    }

    string expression;
    string sortOrder;

    expression = "id > 5";
    // Sort descending by column named CompanyName.
    sortOrder = "name DESC";
    // Use the Select method to find all rows matching the filter.
    DataRow[] foundRows =
        customerTable.Select(expression, sortOrder,
        DataViewRowState.Added);

    PrintRows(foundRows, "filtered rows");

    foundRows = customerTable.Select();
    PrintRows(foundRows, "all rows");
}

private static void PrintRows(DataRow[] rows, string label)
{
    Console.WriteLine("\n{0}", label);
    if(rows.Length <= 0)
    {
        Console.WriteLine("no rows found");
        return;
    }
    foreach(DataRow row in rows)
    {
        foreach(DataColumn column in row.Table.Columns)
        {
            Console.Write("\table {0}", row[column]);
        }
        Console.WriteLine();
    }
}
Private Sub GetRowsByFilter()

    Dim customerTable As New DataTable("Customers")

    ' Add columns
    customerTable.Columns.Add("id", GetType(Integer))
    customerTable.Columns.Add("name", GetType(String))

    ' Set PrimaryKey
    customerTable.Columns("id").Unique = True
    customerTable.PrimaryKey = New DataColumn() _
        {customerTable.Columns("id")}

    ' add ten rows
    Dim id As Integer
    For id = 1 To 10
        customerTable.Rows.Add( _
        New Object() {id, String.Format("customer{0}", id)})
    Next id
    customerTable.AcceptChanges()

    ' add another ten rows
    For id = 11 To 20
        customerTable.Rows.Add( _
        New Object() {id, String.Format("customer{0}", id)})
    Next id

    Dim expression As String
    Dim sortOrder As String

    expression = "id > 5"
    ' Sort descending by CompanyName column.
    sortOrder = "name DESC"

    ' Use the Select method to find all rows matching the filter.
    Dim foundRows As DataRow() = _
        customerTable.Select(expression, sortOrder, _
        DataViewRowState.Added)

    PrintRows(foundRows, "filtered rows")

    foundRows = customerTable.Select()
    PrintRows(foundRows, "all rows")
End Sub

Private Sub PrintRows(ByVal rows() As DataRow, ByVal label As String)
    Console.WriteLine("\n{0}", label)
    If rows.Length <= 0 Then
        Console.WriteLine("no rows found")
        Exit Sub
    End If

    Dim row As DataRow
    Dim column As DataColumn
    For Each row In rows
        For Each column In row.Table.Columns
            Console.Write("\table {0}", row(column))
        Next column
        Console.WriteLine()
    Next row
End Sub

注解

若要形成 filterExpression 参数,请使用与创建 DataColumn 类的属性值相同的规则 ExpressionTo form the filterExpression argument, use the same rules for creating the DataColumn class's Expression property value. Sort参数还使用相同的规则来创建类的 Expression 字符串。The Sort argument also uses the same rules for creating class's Expression strings.

如果筛选器中的列包含 null 值,则它将不是结果的一部分。If the column on the filter contains a null value, it will not be part of the result.

适用于