function addUser(strName)  '成功返回用户id，否者返回-1
    rst.open "tblUser",con,adOpenFowrardOnly,adLockOptimistic,adCmdTable
    rs.addNew
    rst("strName")=xxx ; '这里strName为Unique，重复会报错
    on error resume next 
        rst.update
    if err then  
        addUser=-1
    else
        addUser=rst("lngId")
    end if 
    on error goto 0
end function 

cmd.CommandText="INSERT INTO tblUser (lngId,strName) VALUES (?,?)"
cmd.parameters.append cmd.createParameter("lngId",adInteger,adParamOutput)
cmd.parameters.append cmd.createParameter("strName",adWChar,adParamInput,len(strName),strName)
cmd.execute