SqlCeResultSet.ReadFirst 方法

将阅读器放在 ResultSet 中的第一条记录处。

命名空间: System.Data.SqlServerCe
程序集: System.Data.SqlServerCe（在 system.data.sqlserverce.dll 中）

语法

声明
Public Function ReadFirst As Boolean
用法
Dim instance As SqlCeResultSet
Dim returnValue As Boolean

returnValue = instance.ReadFirst

public bool ReadFirst ()

public:
bool ReadFirst ()

public boolean ReadFirst ()

public function ReadFirst () : boolean

不适用。

返回值

如果操作成功，则为 true；否则为 false。

示例

下面的示例创建一个 ResultSet 对象，然后调用包括 ReadFirst 在内的多个方法。

Dim conn As SqlCeConnection = Nothing

Try
    File.Delete("Test.sdf")

    Dim engine As New SqlCeEngine("Data Source = Test.sdf")
    engine.CreateDatabase()

    conn = New SqlCeConnection("Data Source = Test.sdf")
    conn.Open()

    Dim cmd As SqlCeCommand = conn.CreateCommand()
    cmd.CommandText = "CREATE TABLE myTable (col1 INT)"
    cmd.ExecuteNonQuery()

    cmd.CommandText = "SELECT * FROM myTable"

    Dim rs As SqlCeResultSet = cmd.ExecuteResultSet(ResultSetOptions.Updatable Or ResultSetOptions.Scrollable)

    Dim rec As SqlCeUpdatableRecord = rs.CreateRecord()

    ' Insert 10 records
    '
    Dim i As Integer
    For i = 0 To 9
        rec.SetInt32(0, i)
        rs.Insert(rec)
    Next i

    ' Scroll through the results
    '
    If True = rs.ReadFirst() Then
        MessageBox.Show("col1 = " & rs.GetInt32(0)) 'ordinal
    End If

    If True = rs.ReadRelative(5) Then
        MessageBox.Show("col1 = " & rs.GetInt32(0)) 'ordinal
    End If

    If True = rs.ReadLast() Then
        MessageBox.Show("col1 = " & rs.GetInt32(0)) 'ordinal
    End If

    If True = rs.ReadPrevious() Then
        MessageBox.Show("col1 = " & rs.GetInt32(0)) 'ordinal
    End If

    If True = rs.ReadAbsolute(5) Then
        MessageBox.Show("col1 = " & rs.GetInt32(0)) 'ordinal
    End If
Catch e As Exception
    MessageBox.Show(e.Message)
Finally
    conn.Close()
End Try

SqlCeConnection conn = null;

try
{
    File.Delete("Test.sdf");

    SqlCeEngine engine = new SqlCeEngine("Data Source = Test.sdf");
    engine.CreateDatabase();

    conn = new SqlCeConnection("Data Source = Test.sdf");
    conn.Open();

    SqlCeCommand cmd = conn.CreateCommand();
    cmd.CommandText = "CREATE TABLE myTable (col1 INT)";
    cmd.ExecuteNonQuery();

    cmd.CommandText = "SELECT * FROM myTable";

    SqlCeResultSet rs = cmd.ExecuteResultSet(ResultSetOptions.Updatable | 
        ResultSetOptions.Scrollable);

    SqlCeUpdatableRecord rec = rs.CreateRecord();

    // Insert 10 records
    //
    for (int i = 0; i < 10; i++)
    {
        rec.SetInt32(0, i);
        rs.Insert(rec);
    }

    // Scroll through the results
    //
    if (true == rs.ReadFirst())
    {
        MessageBox.Show("col1 = " + rs.GetInt32(0 /*ordinal*/));
    }

    if (true == rs.ReadRelative(5))
    {
        MessageBox.Show("col1 = " + rs.GetInt32(0 /*ordinal*/));
    }

    if (true == rs.ReadLast())
    {
        MessageBox.Show("col1 = " + rs.GetInt32(0 /*ordinal*/));
    }

    if (true == rs.ReadPrevious())
    {
        MessageBox.Show("col1 = " + rs.GetInt32(0 /*ordinal*/));
    }

    if (true == rs.ReadAbsolute(5))
    {
        MessageBox.Show("col1 = " + rs.GetInt32(0 /*ordinal*/));
    }
}
catch (Exception e)
{
    MessageBox.Show(e.Message);
}
finally
{
    conn.Close();
}

平台

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

Windows Vista、Microsoft Windows XP SP2 和 Windows Server 2003 SP1 支持 Microsoft .NET Framework 3.0。

版本信息

.NET Framework

受以下版本支持：3.0

.NET Compact Framework

受以下版本支持：2.0

请参见

参考

SqlCeResultSet 类
SqlCeResultSet 成员
System.Data.SqlServerCe 命名空间