注意，这假设从不更新键列；一旦一行存在了，它的主键值就不变了。

Note that this assumes that key columns are never updated; once a row exists, it is immutably tied to its primary-key value.

youdao

如果被请求的行存在，则 fetch() 函数返回 TRUE，如果被请求的行不存在，则返回 FALSE。

The fetch() function returns TRUE if the requested row exists and FALSE if the requested row does not exist.

youdao

即使不存在不公平行为，只要简单地声称某一行业受到了进口产品的损害，就足以构成寻求救济的理由。

Even when no unfair practices are alleged, the simple claim that an industry has been injured by imports is sufficient grounds to seek relief.

youdao

And so there are only two kinds of waves that can exist on this violin string, standing or traveling.

由于这只有两种波,可以存在在这条弦上，驻波或行波。

麻省理工公开课 - 固态化学导论课程节选

Someone might also say, you know a little inequality, even a substantial inequality, is not so bad as long as nobody is really suffering.

有些人也可能会说，微小的贫富差距，甚至显著的贫富差距存在，只要没人觉得痛苦就行了。

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