ActiveCommand 属性示例 （VB）

此示例演示 ActiveCommand 属性。

为子例程提供一个 Recordset 对象，该对象 ActiveCommand 属性用于显示创建 Recordset的命令文本和参数。

'BeginActiveCommandVB  
  
    'To integrate this code  
    'replace the data source and initial catalog values  
    'in the connection string  
  
Public Sub Main()  
    On Error GoTo ErrorHandler  
  
        'recordset and connection variables  
    Dim cmd As ADODB.Command  
    Dim rst As ADODB.Recordset  
    Dim Cnxn As ADODB.Connection  
    Dim strCnxn As String  
        'record variables  
    Dim strPrompt As String  
    Dim strName As String  
  
    Set Cnxn = New ADODB.Connection  
    Set cmd = New ADODB.Command  
  
    strPrompt = "Enter an author's name (e.g., Ringer): "  
    strName = Trim(InputBox(strPrompt, "ActiveCommandX Example"))  
    strCnxn = "Provider='sqloledb';Data Source='MySqlServer';" & _  
        "Initial Catalog='Pubs';Integrated Security='SSPI';"  
  
        'create SQL command string  
    cmd.CommandText = "SELECT * FROM Authors WHERE au_lname = ?"  
    cmd.Parameters.Append cmd.CreateParameter("LastName", adChar, adParamInput, 20, strName)  
  
    Cnxn.Open strCnxn  
    cmd.ActiveConnection = Cnxn  
  
        'create the recordset by executing command string  
    Set rst = cmd.Execute(, , adCmdText)  
        'see the results  
    Call ActiveCommandXprint(rst)  
  
    ' clean up  
    Cnxn.Close  
    Set rst = Nothing  
    Set Cnxn = Nothing  
    Exit Sub  
  
ErrorHandler:  
    ' clean up  
    If Not rst Is Nothing Then  
        If rst.State = adStateOpen Then rst.Close  
    End If  
    Set rst = Nothing  
  
    If Not Cnxn Is Nothing Then  
        If Cnxn.State = adStateOpen Then Cnxn.Close  
    End If  
    Set Cnxn = Nothing  
  
    If Err <> 0 Then  
        MsgBox Err.Source & "-->" & Err.Description, , "Error"  
    End If  
End Sub  
'EndActiveCommandVB  

ActiveCommandXprint 例程仅提供 Recordset 对象，但它必须打印创建 Recordset的命令文本和参数。 这样做可能是因为 Recordset 对象的 ActiveCommand 属性生成关联的 Command 对象。

Command 对象的 CommandText 属性生成创建 Recordset的参数化命令。 Command 对象的 Parameters 集合生成替换为命令的参数占位符的值（“？”。

最后，输出错误消息或作者的姓名和 ID。

'BeginActiveCommandPrintVB  
Public Sub ActiveCommandXprint(rstp As ADODB.Recordset)  
  
    Dim strName As String  
  
    strName = rstp.ActiveCommand.Parameters.Item("LastName").Value  
  
    Debug.Print "Command text = '"; rstp.ActiveCommand.CommandText; "'"  
    Debug.Print "Parameter = '"; strName; "'"  
  
    If rstp.BOF = True Then  
       Debug.Print "Name = '"; strName; "', not found."  
    Else  
       Debug.Print "Name = '"; rstp!au_fname; " "; rstp!au_lname; _  
             "', author ID = '"; rstp!au_id; "'"  
    End If  
  
    rstp.Close  
    Set rstp = Nothing  
End Sub  
'EndActiveCommandPrintVB  

另请参阅

ActiveCommand 属性 （ADO）
Command 对象 （ADO）
Recordset 对象 （ADO）