SqlCeResultSet.ReadFirst メソッドとは何？わかりやすく解説 Weblio辞書

.NET Framework クラスライブラリリファレンス

索引トップ用語の索引ランキング

SqlCeResultSet.ReadFirst メソッド

ResultSet 内の最初のレコードにリーダーを移動します。

名前空間: System.Data.SqlServerCe
アセンブリ: System.Data.SqlServerCe (system.data.sqlserverce.dll 内)
構文

Visual Basic (宣言)

Public Function ReadFirst As
 Boolean

Visual Basic (使用法)

Dim instance As SqlCeResultSet
Dim returnValue As Boolean

returnValue = instance.ReadFirst

public bool ReadFirst ()

C++

public:
bool ReadFirst ()

public boolean ReadFirst ()

JScript

public function ReadFirst () : boolean

戻り値
正常に操作できた場合は true。それ以外の場合は false。

使用例

ResultSet オブジェクトを作成して、ReadFirst など、複数のメソッドを呼び出す例を次に示します。

Visual Basic

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