主题：求一个健壮的代码。try catch问题

以下内容为程序代码:

1 try
2 '扑捉错误
3 Connections(_strBooks).BeginTransaction()
4 Dim s As String = Guid.NewGuid.ToString()
5 Dim q As new QueryBuilder
6 q.TableName = "金相临时"
7 q.ConnectionName=_strBooks
8 q.SelectString="EXEC GET_PROJECT_JY '" & _t1 & "','" & Vars("_jxlv_prdno") & "','" & Date.Now() & "','" & s & "'"
9 q.Build
10 ''MessageBox.Show("查询了表成功")
11 Dim i As Integer
12 i=Tables("金相临时").Cols.Count
13 Vars("_int_tbcount")=i
14 Dim j As Integer
15 For j=0 To i-1
16 Tables("金相临时").Cols(j).RecordRowHeight=2
17 Next
18 ''Tables("金相临时").Cols(0).RecordRowHeight=2
19 Dim rgd As WinForm.RecordGrid = e.Form.Controls("RCDG_R")
20 Tables("金相临时").AllowEdit=True
21 rgd.Table=Tables("金相临时")
22 rgd.Build
23 Connections(_strBooks).Commit()
24 catch ex As exception
25 Connections(_strBooks).Rollback
26 MessageBox.Show("错误")
27 Return
28 End try