环境：
系统：WINDOWS SERVER2012 R2
远程数据库ORACLE 19C
本地ORACLE（安装管理员-带有客户端）：12C
数据库名：ORADB (ODBC测试可以连接数据库)
用户名和密码：oraora/oraora
以下是VB的代码，在OPEN时出错。
Set conn_mail = New ADODB.Connection
With conn_mail
.ConnectionTimeout = 500
.ConnectionString = "provider=MSDAORA;Data Source=ORADB;Password=oraora;User ID=oraora" '通过OLEDB建立与数据库的连接
.Open
End With

Private Sub 数据填表()
Dim cn As Object, rs As Object
Set cn = CreateObject("ADODB.Connection")
Set rs = CreateObject("ADODB.Recordset")
'　构成数据库文件连接命令字符串
Dim DbPw As String
Dim DbUser As String
Dim FileName As String
Dim cLink As String '　连接字符串
Dim cSQL As String '　SQL 命令字符串
DbPw = "密码"
DbUser = "用户号"
FileName = "数据库文件名"
cLink = "Provider = MSDAORA.1; Password = DbPw
cLink = cLink & "; User ID = " & DbUser
cLink = cLink & "; Data Source = " & FileName
cLink = cLink & "; Persist Security Info = True"
'　构成【SQL－Select】命令字符串
cSQL = "Select * From 表名"
'　连接并打开数据库表
cn.Open cLink
rs.Open cSQL, cn, 1, 3
'　将数据填表并刷新表格控件
Set MSHFlexGrid1.DataSource = rs
MSHFlexGrid1.Refresh
End Sub

　　如果原来用这个程序就可以打开数据库，现在由于更换了操作系统就不能打开数据库了，多与【操作管理权限】有关，这是网络操作系统的一些设置问题，与应用程序没有什么关系。

完整代码
Private Sub 连接_Click()
Dim conn_mail As ADODB.Connection ' 利用ADO访问数据库
Dim rst_mail As ADODB.Recordset
Dim ssql As String
Set conn_mail = New ADODB.Connection
With conn_mail
.ConnectionTimeout = 500
.ConnectionString = "provider=MSDAORA;Data Source=ORADB;Password=oraora;User ID=oraora" '通过OLEDB建立与数据库的连接
.Open ‘这一步出的错
End With
Set rst_mail = New Recordset
ssql = " select * from oraora.oraora_v "
rst_mail.Open ssql, conn_mail, adOpenKeyset, adLockOptimistic
rst_mail.MoveFirst
End Sub

.ConnectionString = "provider = MSDAORA; Data Source = " & "ORADB" & "; Password = " & "oraora" & "; User ID = " & "oraora"