建立和執行簡單命令

簡單命令是未參數化且不需要持續性的命令。 有三種方式可以建立和執行簡單的命令。

• 使用 指令 物件

• 使用 連線 物件

• 使用 Recordset 物件

使用命令物件

若要使用 Command 物件建立簡單的命令，您必須將指令指派給 Command 物件的 CommandText 属性，並設定 CommandType 屬性的適當值。 執行命令需要將開啟的連接指派給 Command 物件的 ActiveConnection 屬性，然後呼叫 Command 物件上的 Execute 方法。

下列代碼段顯示使用 Command 物件對數據源執行命令的基本方法。 這個範例會使用數據列傳回命令，並將命令執行的結果當做 Recordset 物件傳回。

    'BeginBasicCmd  
    On Error GoTo ErrHandler:  
  
    Dim objConn As New ADODB.Connection  
    Dim objCmd As New ADODB.Command  
    Dim objRs As New ADODB.Recordset  
  
    objCmd.CommandText = "SELECT OrderID, OrderDate, " & _  
                         "RequiredDate, ShippedDate " & _  
                         "FROM Orders " & _  
                         "WHERE CustomerID = 'ALFKI' " & _  
                         "ORDER BY OrderID"  
    objCmd.CommandType = adCmdText  
  
    ' Connect to the data source.  
    Set objConn = GetNewConnection  
    objCmd.ActiveConnection = objConn  
  
    ' Execute once and display...  
    Set objRs = objCmd.Execute  
  
    Debug.Print "ALFKI"  
    Do While Not objRs.EOF  
        Debug.Print vbTab & objRs(0) & vbTab & objRs(1) & vbTab & _  
                    objRs(2) & vbTab & objRs(3)  
        objRs.MoveNext  
    Loop  
  
    'clean up  
    objRs.Close  
    objConn.Close  
    Set objRs = Nothing  
    Set objConn = Nothing  
    Set objCmd = Nothing  
    Exit Sub  
  
ErrHandler:  
    'clean up  
    If objRs.State = adStateOpen Then  
        objRs.Close  
    End If  
  
    If objConn.State = adStateOpen Then  
        objConn.Close  
    End If  
  
    Set objRs = Nothing  
    Set objConn = Nothing  
    Set objCmd = Nothing  
  
    If Err <> 0 Then  
        MsgBox Err.Source & "-->" & Err.Description, , "Error"  
    End If  
'EndBasicCmd  
  
'BeginNewConnection  
Private Function GetNewConnection() As ADODB.Connection  
    Dim oCn As New ADODB.Connection  
    Dim sCnStr As String  
  
    sCnStr = "Provider='SQLOLEDB';Data Source='MySqlServer';" & _  
             "Integrated Security='SSPI';Initial Catalog='Northwind';"  
    oCn.Open sCnStr  
  
    If oCn.State = adStateOpen Then  
        Set GetNewConnection = oCn  
    End If  
  
End Function  
'EndNewConnection  

使用 Recordset 物件

您也可以建立一個文字字串命令，並將其與命令類型 (adCmdText) 一起傳遞至 Recordset 物件上的 Open 方法，以執行該命令。 下列代碼段示範這一點。

  
Const DS = "MySqlServer"  
Const DB = "Northwind"  
Const DP = "SQLOLEDB"  
  
Dim objRs As New ADODB.Recordset  
Dim CommandText As String  
Dim ConnectionString As String  
  
CommandText = "SELECT OrderID, OrderDate, " & _  
                     "RequiredDate, ShippedDate " & _  
                     "FROM Orders " & _  
                     "WHERE CustomerID = 'ALFKI' " & _  
                     "ORDER BY OrderID"  
ConnectionString = "Provider=" & DP & _  
                   ";Data Source=" & DS & _  
                   ";Initial Catalog=" & DB & _  
                   ";Integrated Security=SSPI;"  
  
' Connect to data source and execute the SQL command.  
objRs.Open CommandText, ConnectionString, _  
            adOpenStatic, adLockReadOnly, adCmdText  
  
Debug.Print "ALFKI"  
Do While Not objRs.EOF  
    Debug.Print vbTab & objRs(0) & vbTab & objRs(1) & vbTab & _  
                objRs(2) & vbTab & objRs(3)  
    objRs.MoveNext  
Loop  
  
'Clean up.  
objRs.Close  
Set objRs = Nothing  

使用連線物件

您也可以在開啟的 Connection 物件上執行命令。 先前的程式代碼範例現在會變成：

Const DS = "MySqlServer"  
Const DB = "Northwind"  
Const DP = "SQLOLEDB"  
  
Dim objConn As New ADODB.Connection  
Dim objRs As New ADODB.Recordset  
  
CommandText = "SELECT OrderID, OrderDate, " & _  
                     "RequiredDate, ShippedDate " & _  
                     "FROM Orders " & _  
                     "WHERE CustomerID = 'ALFKI' " & _  
                     "ORDER BY OrderID"  
  
ConnectionString = "Provider=" & DP & _  
                   ";Data Source=" & DS & _  
                   ";Initial Catalog=" & DB & _  
                   ";Integrated Security=SSPI;"  
  
' Connect to the data source.  
objConn.Open ConnectionString  
  
' Execute command through the connection and display...  
Set objRs = objConn.Execute(CommandText)  
  
Debug.Print "ALFKI"  
Do While Not objRs.EOF  
    Debug.Print vbTab & objRs(0) & vbTab & objRs(1) & vbTab & _  
                objRs(2) & vbTab & objRs(3)  
    objRs.MoveNext  
Loop  
  
'Clean up.  
objRs.Close  
objConn.Close  
Set objRs = Nothing  
Set objConn = Nothing