业务规则是对业务的某个方面进行定义或约束的语句。

A business rule is a statement that defines or constrains some aspect of a business.

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安全性约束类似于数据库中的“GRANT”语句。

Security constraints are similar to "GRANT" statements in the database.

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SQL编译器使用信息约束将语句转化成更优的形式，从而改善对所需数据的访问路径。

The SQL compiler USES them to transform a statement into a more optimized form, thus improving the access path to the required data.

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