首先，您通常要具有一个映射到对应数据库表主键的(代理)对象标识符。

First, you usually want to have a (surrogate) object identifier that maps to the primary key of the corresponding database table.

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业务代理又可能会依赖于一个dao对象，而后者又依赖于一个数据库查询或OR映射查询，这样可以对CD进行有效的查询。

The business delegate may in turn rely on a DAO object that in turn relies on a database query or an or mapping query that sorts the CDs very efficiently.

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中间件分数据库、远程过程调用、面向消息、对象请求代理、事务处理管程(TPM)或专用(PM)等类。

The middleware is divided into some classes, such as database, remote procedure call (RPC), oriented message, object request agent, transaction processing management (TPM) or special PM.

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