SQL/XML is good if you want results returned as sets and missing XML elements represented with nulls.

如果您希望将结果作为集合返回，且将丢失的 XML 元素表示为空，那么 SQL/XML 有优势。

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SQL USES a small integer which contains a zero if the column is not null or -1 if the column contains nulls.

如果列不包含空值，则SQL使用一个包含一个0的小整数；反之则包含- 1。

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