我試圖通過在文本框中輸入文本，然后使用SQL查詢數據庫，然后在datagridview中顯示結果，在數據庫中搜索特定值。這是代碼：  Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtSearch.TextChanged    Connection.Open()    Dim dataTable As New DataTable    Dim dataSet As New DataSet    dataSet.Tables.Add(dataTable)    Dim dataAdapter As New OleDbDataAdapter    Dim SQLQuery As String    SQLQuery = <sql>             SELECT *                  FROM Students                 WHERE StudentFirstName = @StudentFirstName                </sql> .Value    dataAdapter = New OleDbDataAdapter(SQLQuery, Connection)    dataAdapter.SelectCommand.Parameters.Add("@StudentFirstName", SqlDbType.Text).Value = txtStudentFirstname.Text    dataAdapter.Fill(dataTable)    dgrStudentDatabaseViewer.DataSource = dataTable.DefaultView    ShowItems()    Connection.Close()End Sub調用ShowItems（）將刷新datagridview，這是它的代碼 Private Sub ShowItems() ' the following delcleration are used for displaying the contents of the table    Dim dataAdapter As New OleDbDataAdapter    Dim DataTable As New DataTable    Dim DataSet As New DataSet    Dim SQLQuery As String = <sql>SELECT * FROM Students</sql>    DataSet.Tables.Add(DataTable)    dataAdapter = New OleDbDataAdapter(SQLQuery, Connection)    dataAdapter.Fill(DataTable) ' fills the content from the database into the table in vb net    dgrStudentDatabaseViewer.DataSource = DataTable.DefaultView    Connection.Close()End Sub此刻，當我嘗試搜索時，什么也沒有發生，datagridview的內容仍然保持不變。我認為這可能與我的SQL Query的XML文字有關，但無法弄清楚。提前致謝。