花姑子熊雄最后得结局:哪个高手可以帮我把这断代码完全的用汉语解释一下

Private Sub bookQuery_Click()
Dim sql As String
Dim rs As ADODB.Recordset
Dim bf(4) As Boolean

sql = "select * from books where "
'判断是否选择按编号查询
If Checkbox(0).Value Then
If Trim(QueryTermNo.Text) = "" Then
MsgBox "图书编号不能为空！", vbOKOnly + vbExclamation, "警告"
QueryTermNo.SetFocus
Exit Sub
Else
bf(0) = True
'组合查询语句
sql = sql & " bookno ='" & Trim(QueryTermNo.Text) & "'"
End If
End If
'判断是否按书名查询
If Checkbox(1) Then
If Trim(QueryTermName.Text) = "" Then
MsgBox "图书名不能为空！", vbOKOnly + vbExclamation, "警告"
QueryTermName.SetFocus
Exit Sub
Else
bf(1) = True
If bf(0) Then
'组和查询语句
sql = sql & " and bookname='" & Trim(QueryTermName.Text) & "'"
Else
sql = sql & " bookname='" & Trim(QueryTermName.Text) & "'"
End If
End If
End If
'判断是否选择按作者查询