Question

我有一个按钮点击运行的查询我想设置它，如果系统日期=＆＃34; DateColumn＆＃34;更新数据库。
其他插入。

    Dim provider As String
    Dim dataFile As String = My.Application.Info.DirectoryPath
    provider = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source ="
    dataFile = ("Database\Base-Original.accdb")

    Using myconnection As New OleDbConnection(provider & dataFile)
        myconnection.Open()

        Dim sqlQry1 As String = "INSERT INTO [Table] ([Column1], [Column2], [Column3], [Column4], [Date]) VALUES (@1, @2, @3, @4, @5)"

        Using cmd As New OleDbCommand(sqlQry1, myconnection)
            cmd.Parameters.AddWithValue("@1", Combobox1.SelectedItem.ToString)
            cmd.Parameters.AddWithValue("@2", textbox1.Text)
            cmd.Parameters.AddWithValue("@3", Textbox2.Text)
            cmd.Parameters.AddWithValue("@4", Combobox2.SelectedItem.ToString)
            cmd.Parameters.AddWithValue("@5", Date.Now.ToShortDateString)

            If cmd.ExecuteNonQuery() Then
                myconnection.Close()
                MsgBox("successfull. ", MsgBoxStyle.Information, "Record Saved")
            Else
                MsgBox("failed. ", MsgBoxStyle.Critical, "Registration failed")
                Return
            End If

        End Using

    End Using

我有INSERT INTO，但我不知道如何更新数据库而不是插入新记录...我知道如何更新，但我想要有一列记录名称（Column1）每天一次。

我是否需要使用阅读器检查日期栏？或者还有另一种方法......我只需指向正确的方向非常感谢..

Answer 1

此处的代码将在数据库中搜索日期值等于今天日期的记录（请参阅下面的重要说明）。如果找到一个，则更新值字段并将其保存回数据库。

    Private Sub SOExample2()
    Using myconnection As New OleDbConnection(provider & dataFile)
        myconnection.Open()
        Dim TodaysRecordSQL As String = String.Format("SELECT [Column1], [Column2], [Column3], [Column4], [Date] FROM [Table] WHERE [Date] = '{0:o}' ORDER BY [Date] DESC", Date.Today.Date)
        Dim UpdateDS As New DataSet
        Using UpdateDA As New OleDb.OleDbDataAdapter(TodaysRecordSQL, myconnection)
            UpdateDA.Fill(UpdateDS)
        End Using
        Dim UpdateTable As DataTable = UpdateDS.Tables("Table")
        If UpdateTable IsNot Nothing AndAlso UpdateTable.Rows.Count = 1 Then
            ' Update existing record
            Dim UpdateRow As DataRow = UpdateTable.Rows(0)
            UpdateRow("Column1") = "NewValue1"
            UpdateRow("Column2") = "NewValue2"
            Using UpdateDA As New OleDb.OleDbDataAdapter()
                Using UpdateCmd As New OleDb.OleDbCommand()
                    UpdateCmd.Connection = myconnection
                    UpdateCmd.CommandText = "UPDATE [Table] SET [Column1] = @1, [Column2] = @2, [Column3] = @3, [Column4] = @4 WHERE [Date] = @5"
                    Dim UpdateParam As OleDb.OleDbParameter = New OleDb.OleDbParameter()
                    UpdateParam.ParameterName = "@1"
                    UpdateParam.SourceColumn = "Column1"
                    UpdateCmd.Parameters.Add(UpdateParam)

                    UpdateParam = New OleDb.OleDbParameter()
                    UpdateParam.ParameterName = "@2"
                    UpdateParam.SourceColumn = "Column2"
                    UpdateCmd.Parameters.Add(UpdateParam)

                    UpdateParam = New OleDb.OleDbParameter()
                    UpdateParam.ParameterName = "@3"
                    UpdateParam.SourceColumn = "Column3"
                    UpdateCmd.Parameters.Add(UpdateParam)

                    UpdateParam = New OleDb.OleDbParameter()
                    UpdateParam.ParameterName = "@4"
                    UpdateParam.SourceColumn = "Column4"
                    UpdateCmd.Parameters.Add(UpdateParam)

                    UpdateParam = New OleDb.OleDbParameter()
                    UpdateParam.ParameterName = "@5"
                    UpdateParam.SourceColumn = "Date"
                    UpdateCmd.Parameters.Add(UpdateParam)

                    UpdateDA.UpdateCommand = UpdateCmd
                    UpdateDA.Update(UpdateDS) ' This does the actual updating of the modified rows in the DataSet
                End Using
            End Using
        Else
            ' Insert new record
        End If
    End Using
End Sub

注意：此代码假设您将记录保存到数据库中，时间戳为00:00小时（即午夜）。如果保存的记录的时间为14:12（下午2:12），那么找到“今天的”记录会比较困难，因为您不知道“今天”条目的时间部分可能是什么

如果日期是今天，＆＃34;更新＆＃34;数据库，否则＆＃34;插入＆＃34;

1 个答案: