ActiveCommand 属性应用实例(VB)

<p><font face="Verdana">ActiveCommand 属性应用实例(VB)</font><br/></p>
<p><font face="Verdana">本范例演示 ActiveCommand 属性。</font></p>
<p><font face="Verdana">为子例程提供了一个 Recordset 对象，该对象的 ActiveCommand 属性用于显示创建 Recordset 的命令文本和参数。</font></p>
<p><font face="Verdana">Public Sub Main()<br/>&nbsp;&nbsp;&nbsp; ActiveCommandX<br/>End Sub</font></p>
<p><font face="Verdana">Public Sub ActiveCommandX()<br/>Dim cnn As New ADODB.Connection<br/>Dim cmd As New ADODB.Command<br/>Dim rst As New ADODB.Recordset<br/>Dim strPrompt As String, strName As String</font></p>
<p><font face="Verdana">strPrompt = "Enter an author's name (e.g., Ringer): "<br/>strName = Trim(InputBox(strPrompt, "ActiveCommandX Example"))<br/>cmd.CommandText = "SELECT * FROM Authors WHERE au_lname = ?"<br/>cmd.Parameters.Append _<br/>&nbsp;&nbsp;&nbsp; cmd.CreateParameter("LastName", adChar, adParamInput, 20, strName)</font></p>
<p><font face="Verdana">cnn.Open "DSN=Pubs;Provider=MSDASQL; uid=sa; pwd=;"<br/>cmd.ActiveConnection = cnn<br/>Set rst = cmd.Execute(, , adCmdText)<br/>ActiveCommandXprint rst</font></p>
<p><font face="Verdana">rst.Close<br/>cnn.Close<br/>End Sub</font></p>
<p><font face="Verdana">对 ActiveCommandXprint 例程仅提供一个 Recordset 对象，而例程必须打印创建 Recordset 的命令文本和参数。由于 Recordset 对象的 ActiveCommand 属性输出相关的 Command 对象，所以可以这么做。</font></p>
<p><font face="Verdana">Command 对象的 CommandText 属性输出创建 Recordset 的参数化命令。Command 对象的 Parameters 集合输出替代命令参数占位符（“?”）的值。</font></p>
<p><font face="Verdana">最后将打印错误消息或作者的名字和 ID。</font></p>
<p><font face="Verdana">Public Sub ActiveCommandXprint(rstp As ADODB.Recordset)<br/>Dim strName As String</font></p>
<p><font face="Verdana">strName = rstp.ActiveCommand.Parameters.Item("LastName").Value</font></p>
<p><font face="Verdana">debug.Print "Command text = '"; rstp.ActiveCommand.CommandText; "'"<br/>Debug.Print "Parameter = '"; strName; "'"</font></p>
<p><font face="Verdana">IF rstp.BOF = True Then<br/>&nbsp;&nbsp;&nbsp; Debug.Print "Name = '"; strName; "', not found."<br/>Else<br/>&nbsp;&nbsp;&nbsp; Debug.Print "Name = '"; rstp!au_fname; " "; rstp!au_lname; _<br/>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; "', author ID = '"; rstp!au_id; "'"<br/>End If</font></p>
<p><font face="Verdana">End Sub</font></p>