為什么每次訪問Access數據庫時VB.Net中的DataGridView大小都會增加一倍？

Question

我這里有一些基本代碼，它們可以調用Access數據庫（“房屋”），僅此而已。 但是，每次單擊按鈕時，DataGridView的大小都會加倍。 我的意思是，如果實際的Access數據庫有5行，DataGridView最初會顯示正確的數據庫，但是每次單擊按鈕后，它最多上升10行（它們重復），然后是15行，然后是20行，等等。不幸的是，我可以請勿將其放置在Form_Load區域中。

我嘗試將“ dt.rows.clear（）”放在“ dgv.DataSource = dt”之前，但它會擦除所有內容。 還嘗試了“ DirectCast（Dgv.DataSource，DataTable）.Rows.Clear（）”和“ Dgv.Datasource = Nothing”

Public Class frmHouses
Dim dt As DataTable = New DataTable()
Dim connStr As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=Houses.accdb"
Dim sqlStr As String = "SELECT * FROM Property"

Private Sub btnRecord_Click(sender As Object, e As EventArgs) Handles btnRecord.Click

    Dim dataAdapter As OleDb.OleDbDataAdapter = New OleDb.OleDbDataAdapter(sqlStr, connStr)

    dataAdapter.Fill(dt)
    dataAdapter.Dispose()

    dgv.DataSource = dt

End Sub

謝謝！

Answer 1

Public Class frmHouses

Dim connStr As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=Houses.accdb"
Dim sqlStr As String = "SELECT * FROM Property"

Private Sub btnRecord_Click(sender As Object, e As EventArgs) Handles btnRecord.Click
    Dim dt As DataTable = New DataTable()
    Dim dataAdapter As OleDb.OleDbDataAdapter = New OleDb.OleDbDataAdapter(sqlStr, connStr)

    dataAdapter.Fill(dt)
    dataAdapter.Dispose()

    dgv.DataSource = dt

End Sub

或者你可以

Public Class frmHouses
Dim dt As DataTable = New DataTable()
Dim connStr As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=Houses.accdb"
Dim sqlStr As String = "SELECT * FROM Property"

Private Sub btnRecord_Click(sender As Object, e As EventArgs) Handles btnRecord.Click
    dt.clear()
    Dim dataAdapter As OleDb.OleDbDataAdapter = New OleDb.OleDbDataAdapter(sqlStr, connStr)

    dataAdapter.Fill(dt)
    dataAdapter.Dispose()

    dgv.DataSource = dt

End Sub

Answer 2

Public Class frmHouses
Dim dt As DataTable = New DataTable()
Dim connStr As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=Houses.accdb"
Dim sqlStr As String = "SELECT * FROM Property"

Private Sub btnRecord_Click(sender As Object, e As EventArgs) Handles btnRecord.Click
    Dim dataAdapter As OleDb.OleDbDataAdapter = New OleDb.OleDbDataAdapter(sqlStr, connStr)
    dataAdapter.Fill(dt)
    dataAdapter.Dispose()
    IF dgv.Rows.Count > 0 Then
    dgv.Rows.Clear()
    End IF
    dgv.DataSource = dt
End Sub