The detail columns, when expanded, are displayed directly below the row that contains the primary columns of data.

具体的列，在扩展时，会直接显示在行的下面，该行包含了数据的主列。

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However, each row must have a unique primary key, which is a sort of name for that particular bundle of data.

不过，每一行的主键(一种用于特定一组数据的名称)必须是唯一的。

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

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。

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