请教 DataAdapter 更新数据问题，更新数据时报错（vb.net）

Question

大家好  请帮我看看这段代码  执行  dadapter.Update(ds, "Writer")时报错    错误提示“ConnectionString 属性尚未初始化”  代码如下

各位高手帮忙看看是怎么回事  先谢谢了 

Public Class Form1

    Public dbconnection As SqlClient.SqlConnection
    Public dbconnectionstring As String
    Dim dadapter As SqlDataAdapter
    Dim dtable As DataTable
    Dim ds As DataSet
    Dim selectstr As String
    Dim selectdbcommand As SqlCommand

    Public Sub opendbconnection()
        dbconnectionstring = "Data Source=LT;Database=sxfx;Integrated Security=SSPI;Persist Security Info=False"
        dbconnection = New SqlClient.SqlConnection(dbconnectionstring)
        Try
            dbconnection.Open()
        Catch ex As Exception
            MsgBox(ex.Message.ToString)
        End Try
    End Sub

    Public Sub closedbconnection()
        dbconnection.Dispose()
        dbconnection.Close()
    End Sub

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        opendbconnection()
       
        selectstr = "select name from  Writer"
        selectdbcommand = New SqlClient.SqlCommand(selectstr, dbconnection)
        dadapter = New SqlDataAdapter(selectdbcommand)
        dtable = New DataTable("Writer")
        ds = New DataSet
        dadapter.Fill(ds, "Writer")
        DataGridView.DataSource = ds.Tables("Writer")

        closedbconnection()

    End Sub

    Private Sub BtUpdate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtUpdate.Click
        opendbconnection()

        Dim scb As SqlCommandBuilder = New SqlCommandBuilder(dadapter)
        dadapter.Update(ds, "Writer")

        closedbconnection()
    End Sub
End Class

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昨夜西风凋碧树，独上高楼，望尽天涯路！

Answer 1

你好！

建议你使用 using 的方式。DataAdapter 的 Fill 方法会自动打开与关闭连接，这里无需其它代码操作。

using (SqlDataAdapter da = new SqlDataAdapter("select name from Writer"
    , "Data Source=LT;Database=sxfx;Integrated Security=SSPI;Persist Security Info=False"))
{
    DataSet ds = new DataSet();
    da.Fill(ds);
    DataGridView.DataSource = ds.Tables[0];
}

 

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知识改变命运，奋斗成就人生!

Answer 2

这样与数据库进行连接和关闭的确不是很好，建议用在using中

using (dbconnection  =new SqlClient.SqlConnection(dbconnectionstring))
{

}