例如 10.2.0.4.x Database PSU 有如下发布，其中最新的是10.2.0.4.5
| Patch | PSU Version |
|---|---|
10.2.0.4.5 | |
10.2.0.4.4 | |
10.2.0.4.3 | |
10.2.0.4.2 | |
10.2.0.4.1 |
10.2.0.4.5 之前的PSU是累积补丁：
Patch Set Update (PSU) patches are cumulative. That is, the content of all previous PSUs is included in the latest PSU patch. PSU 10.2.0.4.4 includes all fixes previously included in PSU 10.2.0.4.3 。
而10.2.0.4.5 要基于之前的10.2.0.4.4 基础上来应用：
Patch Set Update PSU 10.2.0.4.5 is an overlay PSU whose base PSU is
10.2.0.4.4. This patch can only be applied in an Oracle home for which
PSU 10.2.0.4.4 has already been installed.
安装这些PSU要确保你的OPatch是足够新的版本：
You must use the OPatch 10.2 version 10.2.0.4.8 or later to apply this
patch. Oracle recommends that you use the latest released OPatch 10.2,
which is available for download from My Oracle Support patch 6880880 by selecting the 10.2.0.0.0 release.
在安全防范越来越被重视的今天，做好数据库安装规划显得尤为重要。
