DbSeekOptions Enumeration

指定 Seek 方法如何在索引上搜尋的選項。

命名空間: System.Data.SqlServerCe
組件: System.Data.SqlServerCe (在 system.data.sqlserverce.dll)

語法

'宣告
<FlagsAttribute> _
Public Enumeration DbSeekOptions

[FlagsAttribute] 
public enum DbSeekOptions

[FlagsAttribute] 
public enum class DbSeekOptions

/** @attribute FlagsAttribute() */ 
public enum DbSeekOptions

FlagsAttribute 
public enum DbSeekOptions

成員

成員名稱	描述
After	前移到第一個資料列，該資料列具有搜尋值後面的值 (按照索引順序)。
AfterEqual	前移至索引上最後一個符合的資料列。如果沒有符合的資料列，則按照索引順序，前移到具有搜尋值後面之值的第一個資料列。
Before	前移到最後一個資料列，該資料列具有搜尋值後面的值 (按照索引順序)。
BeforeEqual	前移到索引上第一個符合的資料列。如果沒有符合的值，則按照索引順序，前移到具有搜尋值前面之值的最後一個資料列。
FirstEqual	前移到索引上第一個符合的資料列 (按照索引順序)。
LastEqual	前移到索引上最後一個符合的資料列 (按索引順序)。

範例

在此範例中，會針對索引上的 Seek 作業指定 FirstEqual 選項。

Try
    Dim conn As New SqlCeConnection("Data Source = MyDatabase.sdf")
    conn.Open()

    Dim cmd As SqlCeCommand = conn.CreateCommand()
    cmd.CommandType = CommandType.TableDirect
    cmd.IndexName = "Orders_PK"
    cmd.CommandText = "Orders"

    ' We are interested in orders that match Order ID = 10020
    '
    cmd.SetRange(DbRangeOptions.Match, New Object() {10020}, Nothing)

    Dim reader As SqlCeDataReader = cmd.ExecuteReader(CommandBehavior.Default)

    While reader.Read()
        MessageBox.Show(String.Format("{0} ; {1}", reader("Order ID"), reader("Order Date")))
    End While

    ' Now we are interested in orders with Order ID between (10020, 10050)
    '
    cmd.SetRange(DbRangeOptions.InclusiveStart Or DbRangeOptions.InclusiveEnd, New Object() {10020}, New Object() {10050})

    reader = cmd.ExecuteReader(CommandBehavior.Default)

    ' Now seek to Order ID = 10045
    '
    Dim onRow As Boolean =  reader.Seek(DbSeekOptions.FirstEqual, New Object() {10045})

    ' Now ,the reader will return rows with Order ID >= 10045 <= 10050
    ' because the range was set to (10020, 10050)
    '
    If onRow Then
        While reader.Read()
            MessageBox.Show(String.Format("{0} ; {1}", reader("Order ID"), reader("Order Date")))
        End While
    End If
Catch e As Exception
    MessageBox.Show(e.Message)
End Try

try
{
    SqlCeConnection conn = new SqlCeConnection("Data Source = MyDatabase.sdf");
    conn.Open();

    SqlCeCommand cmd = conn.CreateCommand();
    cmd.CommandType = CommandType.TableDirect;
    cmd.IndexName = "Orders_PK";
    cmd.CommandText = "Orders";

    // We are interested in orders that match Order ID = 10020
    //
    cmd.SetRange(DbRangeOptions.Match, new object[] { 10020 }, null);

    SqlCeDataReader reader = cmd.ExecuteReader(CommandBehavior.Default);

    for (int i = 1; reader.Read(); i++)
    {
        MessageBox.Show(String.Format("{0} ; {1}", reader["Order ID"], reader["Order Date"]));
    }

    // Now we are interested in orders with Order ID between (10020, 10050)
    //
    cmd.SetRange(DbRangeOptions.InclusiveStart | DbRangeOptions.InclusiveEnd,
        new object[] { 10020 }, new object[] { 10050 });

    reader = cmd.ExecuteReader(CommandBehavior.Default);

    // Now seek to Order ID = 10045
    //
    bool onRow = reader.Seek(DbSeekOptions.FirstEqual, new object[] { 10045 });

    // Now ,the reader will return rows with Order ID >= 10045 <= 10050
    // because the range was set to (10020, 10050)
    //
    if (onRow)
    {
        for (int i = 1; reader.Read(); i++)
        {
            MessageBox.Show(String.Format("{0} ; {1}", reader["Order ID"], reader["Order Date"]));
        }
    }
}
catch (Exception e)
{
    MessageBox.Show(e.Message);
}

平台

開發平台

Windows Vista, Windows Mobile 5.0, Windows XP Professional with Service Pack 2 (SP2), Windows Server 2003, Windows Mobile 2003 for Pocket PC, Windows CE 5.0
版本資訊
.NET Framework 及 NET Compact Framework
支援於 3.5
.NET Framework
支援於 3.0
.NET Compact Framework 及 .Net Framework
支援於 2.0

另請參閱

參考

System.Data.SqlServerCe Namespace