Item 属性示例 (VB)
此示例演示 Item 属性如何访问集合的成员。 该示例使用参数化命令打开 Pubs 数据库的 Authors 表。
针对数据库发出的命令中的参数按索引和名称从 Command 对象的 Parameters 集合进行访问。 然后按索引和名称从该对象的 Fields 集合访问返回的 Recordset 的字段。
'BeginItemVB
'To integrate this code
'replace the data source and initial catalog values
'in the connection string
Public Sub Main()
On Error GoTo ErrorHandler
Dim Cnxn As ADODB.Connection
Dim rstAuthors As ADODB.Recordset
Dim cmd As ADODB.Command
Dim prm As ADODB.Parameter
Dim fld As ADODB.Field
Dim strCnxn As String
Dim ix As Integer
Dim limit As Long
Dim Column(0 To 8) As Variant
Set Cnxn = New ADODB.Connection
Set rstAuthors = New ADODB.Recordset
Set cmd = New ADODB.Command
'Set the array with the Authors table field (column) names
Column(0) = "au_id"
Column(1) = "au_lname"
Column(2) = "au_fname"
Column(3) = "phone"
Column(4) = "address"
Column(5) = "city"
Column(6) = "state"
Column(7) = "zip"
Column(8) = "contract"
cmd.CommandText = "SELECT * FROM Authors WHERE state = ?"
Set prm = cmd.CreateParameter("ItemXparm", adChar, adParamInput, 2, "CA")
cmd.Parameters.Append prm
' set connection
strCnxn = "Provider='sqloledb';Data Source='MySqlServer';" & _
"Initial Catalog='Pubs';Integrated Security='SSPI';"
Cnxn.Open strCnxn
cmd.ActiveConnection = Cnxn
' open recordset
rstAuthors.Open cmd, , adOpenStatic, adLockReadOnly
'Connection and CommandType are omitted because
'a Command object is provided
Debug.Print "The Parameters collection accessed by index..."
Set prm = cmd.Parameters.Item(0)
Debug.Print "Parameter name = '"; prm.Name; "', value = '"; prm.Value; "'"
Debug.Print
Debug.Print "The Parameters collection accessed by name..."
Set prm = cmd.Parameters.Item("ItemXparm")
Debug.Print "Parameter name = '"; prm.Name; "', value = '"; prm.Value; "'"
Debug.Print
Debug.Print "The Fields collection accessed by index..."
rstAuthors.MoveFirst
limit = rstAuthors.Fields.Count - 1
For ix = 0 To limit
Set fld = rstAuthors.Fields.Item(ix)
Debug.Print "Field "; ix; ": Name = '"; fld.Name; _
"', Value = '"; fld.Value; "'"
Next ix
Debug.Print
Debug.Print "The Fields collection accessed by name..."
rstAuthors.MoveFirst
For ix = 0 To 8
Set fld = rstAuthors.Fields.Item(Column(ix))
Debug.Print "Field name = '"; fld.Name; "', Value = '"; fld.Value; "'"
Next ix
' clean up
rstAuthors.Close
Cnxn.Close
Set rstAuthors = Nothing
Set Cnxn = Nothing
Exit Sub
ErrorHandler:
' clean up
If Not rstAuthors Is Nothing Then
If rstAuthors.State = adStateOpen Then rstAuthors.Close
End If
Set rstAuthors = Nothing
If Not Cnxn Is Nothing Then
If Cnxn.State = adStateOpen Then Cnxn.Close
End If
Set Cnxn = Nothing
Set cmd = Nothing
If Err <> 0 Then
MsgBox Err.Source & "-->" & Err.Description, , "Error"
End If
End Sub
'EndItemVB