Constraints Supports, primary, foreign, unique, not null constraint.

约束 支持主键、外键、惟一和非空约束。

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The portlet will automatically receive these parameters if they are not null.

如果这些参数不是空值，Portlet将自动接收它们。

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Before using objects like rows and cells, be sure to test them to make sure they are not null.

在使用行和单元格这样的对象之前，一定要测试它们，确保它们不为空。

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If the stock is not produced, then the shorting transaction will be null and void and the broker will have to purchase the stock, says Jamie Selway, managing director at White Cap Trading.

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As a result, Botha has turned to the courts in an attempt to have his Bulls contract declared null and void, while Sarfu has not confirmed whether his Springbok contract is part of his court application.

BBC: Strike threat to Springbok tour

Translation, if one were to start with a pre-trial null hypothesis probability of 50% (reflecting equipoise, an ethical prerequisite for randomizing patients), the post-trial null hypothesis probability would still be 9%, which is not sufficient to change my practice.

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