Because of performance problems using EJB2 queries, we decided a long time ago to use direct JDBC calls for query operations and EJB2 CMP for create, retrieve, update, and delete (CRUD) operations.

由于使用e JB 2查询存在性能问题，我们很早就决定对于查询操作使用直接JDBC调用，而对于创建、检索、更新和删除(CRUD)操作则使用EJB2 CMP。

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It also calls its implementation query and, as before, you give it a CSS selector and it gives you a collection (see Listing 4).

它也调用它的查询实现，同上面一样，您给它一个CSS选择器，它就返回一个元素集(如清单4所示)。

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As stated earlier, we used direct JDBC calls for our complex query operations to avoid the performance overhead in EJB2 query.

如前所述，对于复杂的查询操作，我们使用了直接JDBC调用，从而避免EJB 2查询中的性能开销。

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