我的主要目標是撰寫導航按鈕來控制與 Microsoft Access 資料庫連接的vb.net專案的記錄。包括的四個按鈕是第一條記錄、最后一條記錄、下一條記錄和上一條記錄。顯示的錯誤說“ShowData”和“CurrentRow”沒有宣告。
CurrentRow 顯示以下糾錯選項：
ShowData 顯示以下糾錯選項：
'to navigate to first record
Private Sub btn_first_Click(sender As Object, e As EventArgs) Handles btn_first.Click
CurrentRow = 0
ShowData(CurrentRow)
End Sub
'to navigate to last record
Private Sub btn_last_Click(sender As Object, e As EventArgs) Handles btn_last.Click
CurrentRow = Dst.Tables("Purchases_file").Rows.Count - 1
ShowData(CurrentRow)
End Sub
'to navigate to previous record
Private Sub btn_previous_Click(sender As Object, e As EventArgs) Handles btn_previous.Click
If CurrentRow <> 0 Then
CurrentRow -= 1
ShowData(CurrentRow)
Else
MsgBox("First record is reached!", MsgBoxStyle.Exclamation)
End If
End Sub
'to navigate to next record
Private Sub btn_next_Click(sender As Object, e As EventArgs) Handles btn_next.Click
If CurrentRow = Dst.Tables("Purchases_file").Rows.Count - 1 Then
MsgBox("Last record is reached!", MsgBoxStyle.Exclamation)
Else
CurrentRow = 1
ShowData(CurrentRow)
End If
End Sub
uj5u.com熱心網友回復：
根據您得到的錯誤，您在方法中使用它之前沒有宣告 CurrentRow。放
Private CurrentRow as Integer
在你的課堂上。ShowData 呼叫該方法從資料庫中檢索資料。它應該是這樣的：
Private Sub ShowData(byval row as integer)
'code to get the data in the database
End Function
如果變數和方法存在于專案的另一個類中，您需要通過它們的類來參考它們。例如：
ClassName.CurrentRow
ClassName.ShowData(CurrentRow)
uj5u.com熱心網友回復：
我的 Roasters 表的欄位名稱為 Name、City 和 Zip。它們系結到BindingNavigator表單上的標簽，也是一個DataGridView. 在BindingNavigator提供您所描述的按鈕。
匯入 System.Data.SqlClient
公共類 BindingNavigator
Dim WithEvents bindSrc As New BindingSource
Private Sub BindingNavigator_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim dt = LoadData1()
bindSrc.DataSource = dt
BindingNavigator1.BindingSource = bindSrc
lblItem.DataBindings.Add(New Binding("Text", bindSrc, "Name"))
lblDescription.DataBindings.Add(New Binding("Text", bindSrc, "City"))
lblPrice.DataBindings.Add(New Binding("Text", bindSrc, "Zip"))
DataGridView1.DataSource = bindSrc
End Sub
Private Function LoadData1() As DataTable
Dim dt As New DataTable
Using conn As New SqlConnection(My.Settings.CoffeeConnection),
cmd As New SqlCommand("Select Top 10 * From Roasters;", conn)
conn.Open()
dt.Load(cmd.ExecuteReader)
End Using
Return dt
End Function
結束類
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