我用下面程序写数据库,能够写入,但是写入数据库的位置有时在中间,有时在最后.我想让他一直加在数据库最后一条,应该怎么改呢?

Sub procedure2

Dim strcn,cn,objTag_num,objTag_piece,objTag_length
Dim is_SQL,rscom
Set cn=CreateObject("ADODB.Connection")
Set rscom=CreateObject("ADODB.Recordset")

objTag_num=HMIRuntime.Tags("ttag_num").Read
objTag_piece=HMIRuntime.Tags("ttag_piece").Read
objTag_length=HMIRuntime.Tags("ttag_length").Read
is_SQL ="insert into database_test1(num,piece,length,date) Values('"&objTag_num&"','"&objTag_piece&"','"&objTag_length&"','"&Now&"')"

strcn="Provider=SQLOLEDB.1;Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=database_test;Data Source=LUO\wincc"
cn.ConnectionString=strcn
cn.Open

cn.Execute is_SQL
cn.close
End Sub