设计形式良好的循环嵌套和流程片断分支，将是降低出现建模错误的可能性的有效方式。

A well-formed nesting of cyclic and branching process fragments is a good approach to reduce the possibility of modeling errors.

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因为嵌套循环联接的工作方式，所以每隔一个外部表记录执行第二步(共4个节点)。

Because of how nested loop joins work, the second leg (there are four nodes) is executed per outer table record.

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