Item 属性范例 (VB)

本范例演示 Item 属性访问集合成员的方式。本范例使用参数化命令打开 Pubs 数据库的 Authors 表。

从 Command 对象的 Parameters 集合中，按照索引和名称访问针对数据库发出的命令中的参数。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。

Public Sub Main()
    ItemX
End Sub

Public Sub ItemX()
Dim cnn As ADODB.Connection
Dim rst As ADODB.Recordset
Dim cmd As ADODB.Command
Dim prm As ADODB.Parameter
Dim fld As ADODB.Field
Dim ix As Integer
Dim limit As Long
Dim Column(0 To 8) As Variant

Set cnn = New ADODB.Connection
Set rst = 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

cnn.Open "DSN=Pubs;Provider=MSDASQL; uid=sa;pwd=;"
cmd.ActiveConnection = cnn
'Connection and CommandType are omitted because a Command object is
'provided.
rst.Open cmd, , adOpenStatic, adLockReadOnly

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..."
rst.MoveFirst
limit = rst.Fields.Count - 1
For ix = 0 To limit
    Set fld = rst.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..."
rst.MoveFirst
For ix = 0 To 8
    Set fld = rst.Fields.Item(Column(ix))
    Debug.Print "Field name = '"; fld.name; "', Value = '"; fld.Value; "'"
Next ix

rst.Close
cnn.Close
End Sub