vb6 - 这段 Visual Basic 6.0 代码有什么作用？

Question

下面这段 Visual Basic 6.0 代码的作用是什么？但是它已被用于搜索功能，我不清楚。所以请解释它的作用。

Private Sub cmdSearch_Click()
    Dim key As Integer, str As String
    key = InputBox("Enter the Employee No whose details u want to know: ")
    Set rs = Nothing
    str = "select * from emp where e_no=" & key
    rs.Open str, adoconn, adOpenForwardOnly, adLockReadOnly
    txtNo.Text = rs(0)
    txtName.Text = rs(1)
    txtCity.Text = rs(2)
    txtDob.Text = rs(4)
    txtPhone.Text = rs(3)
    Set rs = Nothing
    str = "select * from emp"
    rs.Open str, adoconn, adOpenDynamic, adLockPessimistic
End Sub

Answer 1

还没有人明确指出的一点是，rs 必须声明为 As New RecordSet，这样 Set rs = Nothing 就意味着有效与 Set rs = New RecordSet 相同。