超菜，请帮我解释一下这几条语句！

realWeboy 2003-09-13 09:35:00

Public Sub RestoreDataBase()
If Text1.Text = "" Then
MsgBox "请选择要恢复的数据文件！", vbInformation, "提示"
Exit Sub
Else
ret = MsgBox("数据恢复操作将会覆盖以前的所有数据并且覆盖后无法恢复，您确定要进行恢复操作吗？", vbQuestion + vbOKCancel, "提示")
If ret = vbOK Then
Dim cn As New ADODB.Connection
Dim sn As New ADODB.Recordset
Dim s_restore As String
Me.MousePointer = 11
cn.Open "Provider=SQLOLEDB.1;Persist Security Info=False;server=" & d1 & ";Initial Catalog=master;Data Source=127.0.0.1;user id=sa;password=" & d3 & ""
sn.Open "select spid from sysprocesses where dbid=db_id('student1')", cn
Do While Not sn.EOF
cn.Execute "kill " & sn("spid")
sn.MoveNext
Loop
sn.Close
s_restore = "restore database student1 from disk='" + Trim(Text1.Text) + "' with REPLACE"
cn.Execute s_restore
'Debug.Print gs_conn_string
'此时需要连接master数据库才能完成数据恢复操作
'同上student1为需要恢复的数据库
s_restore = "restore database student1 from disk='" + Trim(Text1.Text) + "'"
'text1一个用于记录需要恢复文件的地址的textbox
cn.Execute s_restore
cn.BeginTrans
If Err.Number = 0 Then
cn.CommitTrans
MsgBox "数据恢复成功！", vbInformation, "提示"
Command1.Enabled = True
Label1.Visible = False
Else
cn.RollbackTrans
MsgBox "数据恢复失败！", vbCritical, "提示"
Command1.Enabled = True
End If
cn.Close
Set cn = Nothing
Me.MousePointer = 1
Else
Exit Sub
End If
On Error Resume Next
Dim DBC As New DataBaseConnection
If db.State = 1 Then
db.Close
End If
db.ConnectionString = DBC.SqlConnectString(d1, d2, d3)
rs.CursorType = adOpenDynamic
rs.CursorLocation = adUseClient
rs.LockType = adLockOptimistic
db.CursorLocation = adUseClient
db.Open
Set cmd.ActiveConnection = db
If Err.Number Then
MsgBox Err.Description, 16 + vbOKOnly, Err.Number
Exit Sub
End If
db.DefaultDatabase = "student1"
If Err.Number Then
MsgBox Err.Description, 16 + vbOKOnly, Err.Number
Exit Sub
End If
End If
End Sub

在上面那段代码中的，下面几条语句，我觉得没必要写，请帮我解释一下有什么作用好吗？
---------------------------------------------------------------------
sn.Open "select spid from sysprocesses where dbid=db_id('student1')", cn
Do While Not sn.EOF
cn.Execute "kill " & sn("spid")
sn.MoveNext
Loop
sn.Close
----------------------------------------------------------------------
On Error Resume Next
Dim DBC As New DataBaseConnection
If db.State = 1 Then
db.Close
End If
db.ConnectionString = DBC.SqlConnectString(d1, d2, d3)
rs.CursorType = adOpenDynamic
rs.CursorLocation = adUseClient
rs.LockType = adLockOptimistic
db.CursorLocation = adUseClient
db.Open
Set cmd.ActiveConnection = db
If Err.Number Then
MsgBox Err.Description, 16 + vbOKOnly, Err.Number
Exit Sub
End If
db.DefaultDatabase = "student1"
If Err.Number Then
MsgBox Err.Description, 16 + vbOKOnly, Err.Number
Exit Sub
End If
---------------------------------------------------------------------
谢了！！！

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