Question

我正在使用MS Access数据库。现在我必须更新特定的单元格值。这是我的代码：

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

Dim str As String
Dim Presc As New System.Text.StringBuilder
Dim prs As String(), j As Integer
prs = Split(txtPrescription.Text, vbCrLf)
For j = 0 To prs.Length - 1
    Presc.Append(prs(j))
    Presc.Append(",")
Next
Try
    str = Trim(lsvCase.SelectedItems(0).Text)
    'MessageBox.Show(str)
    Dim con As System.Data.OleDb.OleDbConnection
    Dim ds As New DataSet
    Dim rea As System.Data.OleDb.OleDbDataReader
    con = New OleDb.OleDbConnection
    Dim da As New System.Data.OleDb.OleDbDataAdapter
    con.ConnectionString = "Provider = Microsoft.ACE.OLEDB.12.0; Data Source= F:\Sowmya Laptop Backups\sowdb1.accdb;"
    con.Open()
    Dim cmd As OleDb.OleDbCommand = con.CreateCommand
    cmd.CommandText = "UPDATE Casehistory set Prescription =' " & Presc.ToString() & "'"
    rea = cmd.ExecuteReader
    cmd.ExecuteNonQuery()
    da.FillSchema(ds, SchemaType.Mapped)
    da.Update(ds, "Casehistory")
    con.Close()
Catch ex As Exception
Finally
End Try
End Sub

此代码更新该列中的所有单元格。我想只更新具有Case_ID = str的特定单元格我必须添加WHERE子句（WHERE Case_ID =“＆amp; str＆amp;”

Answer 1

我会使用命令参数，neater并防止SQL注入问题。类似的东西：

cmd.CommandText = "UPDATE Casehistory set Prescription =@Presc WHERE Case_ID = @CaseID"
cmd.Parameters.AddWithValue("@Presc", Presc.ToString())
cmd.Parameters.AddWithValue("@CaseID",str)

顺便说一句，在按钮点击事件中包含所有这些代码并不理想。您可能希望以更易于维护的方式调查构建应用程序 - 例如，可能使用Data Layer。

Answer 2

Where子句应附加到OleDbCommmand.CommandText的末尾，您可以在其中定义Update语句。

在VB.net中更新数据库表的单个单元格

2 个答案: