Seek 方法和 Index 属性范例 (VB)

本范例使用 Recordset 对象的 Seek 方法、Index 属性和给定的 Employee ID，在 Nwind.mdb 数据库的 Employees 表中定位雇员名。

Public Sub Main()
    SeekX
End Sub

Public Sub SeekX()
Dim rst As ADODB.Recordset
Dim strID As String
Dim strPrompt As String
strPrompt = "Enter an EmployeeID (e.g., 1 to 9)"

Set rst = New ADODB.Recordset
rst.CursorLocation = adUseServer
rst.Open "employees", _
                "Provider=Microsoft.Jet.OLEDB.4.0;" & _
                "Data Source=c:tempnorthwind.mdb;" & _
                "user id=admin;password=;", _
                adOpenKeyset, adLockReadOnly, adCmdTableDirect

' Does this provider support Seek and Index?
If rst.Supports(adIndex) And rst.Supports(adSeek) Then
rst.Index = "EmployeeId"
' Display all the employees.
        rst.MoveFirst
        Do While rst.EOF = False
            Debug.Print rst!EmployeeID; ": "; rst!firstname; " "; _
                            rst!LastName
            rst.MoveNext
        Loop
   
' Prompt the user for an EmployeeID between 1 and 9.
        rst.MoveFirst
        Do
            strID = LCase(Trim(InputBox(strPrompt, "Seek Example")))
            ' Quit if strID is a zero-length string (CANCEL, null, etc.)
            If Len(strID) = 0 Then Exit Do
            If Len(strID) = 1 And strID >= "1" And strID <= "9" Then
                rst.Seek Array(strID), adSeekAfterEQ
                If rst.EOF Then
                    Debug.Print "Employee not found."
                Else
                    Debug.Print strID; ": Employee='"; rst!firstname; " "; _
                    rst!LastName; "'"
                End If
            End If
        Loop
End If

rst.Close
End Sub