Question

我正在处理我正在处理的代码问题，我已经搜索过，似乎找不到任何可以帮助我的东西！

Public Class CustomerController

Public Const CONNECTION_STRING As String = _
  "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=assignment.accdb"

Public Sub insert(ByVal htData As Hashtable)

    Dim oConnection As OleDbConnection = New OleDbConnection(CONNECTION_STRING)

    Try
        Debug.Print("Connection string: " & oConnection.ConnectionString)

        oConnection.Open()
        Dim oCommand As OleDbCommand = New OleDbCommand
        oCommand.Connection = oConnection


        oCommand.CommandText = _
           "INSERT INTO customer (title, gender, firstname, lastname, phone, address, email, dob) VALUES (?, ?, ?, ?, ?, ?, ?, ?);"
        oCommand.Parameters.Add("title", OleDbType.VarChar, 255)
        oCommand.Parameters.Add("gender", OleDbType.VarChar, 255)
        oCommand.Parameters.Add("firstname", OleDbType.VarChar, 255)
        oCommand.Parameters.Add("lastname", OleDbType.VarChar, 255)
        oCommand.Parameters.Add("phone", OleDbType.VarChar, 255)
        oCommand.Parameters.Add("address", OleDbType.VarChar, 255)
        oCommand.Parameters.Add("email", OleDbType.VarChar, 255)
        oCommand.Parameters.Add("dob", OleDbType.VarChar, 255)



        oCommand.Parameters("title").Value = CStr(htData("title"))
        oCommand.Parameters("gender").Value = CStr(htData("gender"))
        oCommand.Parameters("firstname").Value = CStr(htData("firstname"))
        oCommand.Parameters("lastname").Value = CStr(htData("lastname"))
        oCommand.Parameters("phone").Value = CStr(htData("phone"))
        oCommand.Parameters("address").Value = CStr(htData("address"))
        oCommand.Parameters("email").Value = CStr(htData("email"))
        oCommand.Parameters("dob").Value = CStr(htData("dob"))

        oCommand.Prepare()

        Debug.Print("SQL: " & oCommand.CommandText)

        oCommand.ExecuteNonQuery()

        Debug.Print("The record was inserted.")

        'If an error has occurred, this will show an error message to inform user that the record was not inserted
    Catch ex As Exception
        Debug.Print("ERROR: " & ex.Message)
        MsgBox("An error occurred. The record wasn't inserted.")
    Finally
        oConnection.Close()
    End Try

End Sub

结束班

当我输入是将数据插入我的数据库时，我收到消息“错误：参数？_1没有默认值” 如果有人能帮助我，真的很感激!!感谢!!!

Answer 1

试试这个。如果这不起作用，则数据库中可能存在一个需要值但未提供任何值的列，或者查询中可能缺少该列。此外，使用“使用块”自动处理诸如连接和命令之类的对象也是一件好事。

Public Const CONNECTION_STRING As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=assignment.accdb"

Public Sub insert(htData As Hashtable)
    Try
        Using cn = New OleDbConnection(CONNECTION_STRING)
            cn.Open()
            Using cmd = New OleDbCommand("INSERT INTO Customer (title, gender, firstname, lastname, phone, address, email, dob) VALUES (?,?,?,?,?,?,?,?)", cn)
                With cmd.Parameters
                    .AddWithValue("title", htData("title"))
                    .AddWithValue("gender", htData("gender"))
                    .AddWithValue("firstname", htData("firstname"))
                    .AddWithValue("lastname", htData("lastname"))
                    .AddWithValue("phone", htData("phone"))
                    .AddWithValue("address", htData("address"))
                    .AddWithValue("email", htData("email"))
                    .AddWithValue("dob", htData("dob"))
                End With

                cmd.ExecuteNonQuery()
            End Using
        End Using

        Debug.Print("The record was inserted.")

        'If an error has occurred, this will show an error message to inform user that the record was not inserted
    Catch ex As Exception
        Debug.Print("ERROR: " & ex.Message)
        MsgBox("An error occurred. The record wasn't inserted.")
    End Try
End Sub

Answer 2

你可以试试这个：

    oCommand.Parameters("title").Value = IIf(CStr(htData("title")) = "", DBNull.Value, CStr(htData("title")))
    oCommand.Parameters("gender").Value = IIf(CStr(htData("gender")) = "", DBNull.Value, CStr(htData("gender")))
    oCommand.Parameters("firstname").Value = IIf(CStr(htData("firstname")) = "", DBNull.Value, CStr(htData("firstname")))
    oCommand.Parameters("lastname").Value = IIf(CStr(htData("lastname")) = "", DBNull.Value, CStr(htData("lastname")))
    oCommand.Parameters("phone").Value = IIf(CStr(htData("phone")) = "", DBNull.Value, CStr(htData("phone")))
    oCommand.Parameters("address").Value = IIf(CStr(htData("address")) = "", DBNull.Value, CStr(htData("address")))
    oCommand.Parameters("email").Value = IIf(CStr(htData("email")) = "", DBNull.Value, CStr(htData("email")))
    oCommand.Parameters("dob").Value = IIf(CStr(htData("dob")) = "", DBNull.Value, CStr(htData("dob")))

Visual studio：错误：参数？_1没有默认值

2 个答案: