Ms access 在vbnet中加载的位置选择最大值（id）

从表中获取最后一个

id

的值时遇到问题

由于加载整个列将在将来给我带来问题（

DataTable

有其局限性），因此我决定寻找另一种解决方案，但我没有运气让它工作

我有string命令，但不知道将返回值存储在哪里。 这是我的密码：

        Dim query As String = "SELECT MAX(id) AS LastId FROM Table1"
    Dim dtmain As New DataTable
    Try
        With sqlcmd
            .CommandText = query
            .Connection = sqlcon
        End With

        With sqladp
            .SelectCommand = sqlcmd
            .Fill(dtMain)
        End With
        MsgBox("last id = " & dtmain.Rows(0)("LastId"))
    Catch ex As Exception

    End Try

我什么也没得到，

msgbox

甚至都不会显示

注意：我想要表中最后一个

id

，而不是插入的

id

以下是我的参考和声明：

   Imports System.Data.OleDb
    Private conn As OleDbConnection
    Private adapter As OleDbDataAdapter
    Private cmdd As OleDbCommand

---

此外，如果您的数据源位于当前数据库中，我还在我的项目参考中添加了用于DDL和安全性的Microsoft ADO Ext 2.8

Dim dbConnect As Database
Dim rstRecordset As DAO.Recordset

Set dbConnect = Access.CurrentDb

Dim query As String = "SELECT MAX(id) AS LastId FROM Table1"

Set rstRecordset = dbConnect .OpenRecordset(query)
MsgBox("last id = " & rstRecordset.Fields(0).value & ""))

dbConnect.Close
Set dbConnect = Nothing
Set rstRecordset = Nothing

Dim cnnConn As ADODB.connection
Dim rstRecordset As ADODB.Recordset
Dim cmdCommand As ADODB.Command

' Open the connection.
Set cnnConn = New ADODB.connection
With cnnConn
    .ConnectionString = _
        "Provider=Microsoft.Jet.OLEDB.4.0"
     .Properties("Jet OLEDB:Database Password") = "pass"
     .Open "D:\Databases\Database.mdb"
End With

' Set the command text.
Set cmdCommand = New ADODB.Command
Set cmdCommand.ActiveConnection = cnnConn
With cmdCommand
    .CommandText = "SELECT MAX(id) AS LastId FROM Table1"
    .CommandType = adCmdText
    .Execute
End With

' Open the recordset.
Set rstRecordset = New ADODB.Recordset
Set rstRecordset.ActiveConnection = cnnConn
rstRecordset.Open cmdCommand
MsgBox("last id = " & rstRecordset.Fields(0).value & ""))

' Close the connections and clean up.
cnnConn.Close
Set cmdCommand = Nothing
Set rstRecordset = Nothing
Set cnnConn = Nothing

---

如果数据源位于另一个Access数据库中：

Dim dbConnect As Database
Dim rstRecordset As DAO.Recordset

Set dbConnect = Access.CurrentDb

Dim query As String = "SELECT MAX(id) AS LastId FROM Table1"

Set rstRecordset = dbConnect .OpenRecordset(query)
MsgBox("last id = " & rstRecordset.Fields(0).value & ""))

dbConnect.Close
Set dbConnect = Nothing
Set rstRecordset = Nothing

Dim cnnConn As ADODB.connection
Dim rstRecordset As ADODB.Recordset
Dim cmdCommand As ADODB.Command

' Open the connection.
Set cnnConn = New ADODB.connection
With cnnConn
    .ConnectionString = _
        "Provider=Microsoft.Jet.OLEDB.4.0"
     .Properties("Jet OLEDB:Database Password") = "pass"
     .Open "D:\Databases\Database.mdb"
End With

' Set the command text.
Set cmdCommand = New ADODB.Command
Set cmdCommand.ActiveConnection = cnnConn
With cmdCommand
    .CommandText = "SELECT MAX(id) AS LastId FROM Table1"
    .CommandType = adCmdText
    .Execute
End With

' Open the recordset.
Set rstRecordset = New ADODB.Recordset
Set rstRecordset.ActiveConnection = cnnConn
rstRecordset.Open cmdCommand
MsgBox("last id = " & rstRecordset.Fields(0).value & ""))

' Close the connections and clean up.
cnnConn.Close
Set cmdCommand = Nothing
Set rstRecordset = Nothing
Set cnnConn = Nothing

---

未定义错误1类型“DAO.Recordset”。未声明错误2“CurrentDB”。由于它的保护级别，它可能无法访问。“我试图通过添加“Microsoft ActiveX Data Objects 2.x Library”来修复错误，但没有修复第二个错误。”我将添加我的参考资料，可能会有所帮助。在我完全利用该功能之前，我似乎需要学习adodb。。。我现在就投赞成票：）