Optional clause to be used only where appropriate.

只有在适当的情况下才使用选择条款。

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Since DB2 9.5 you can add the optional clause REJECT INVALID VALUES to your XML index definition.

从DB 2 9.5往后，您就可以向xml索引定义添加可选的REJECT INVALID values子句。

youdao

BULK COLLECT is not a statement on its own, but an optional clause that can be applied to SELECT INTO and FETCH statements.

BULK COLLECT自身不是语句，而是可用于SELECT INTO和fetch语句的可选子句。

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