与RDBMS索引相似，可以使用多个属性创建复合索引，也可创建唯一索引，确保不存在重复的值。
Like RDBMS indexes, you can create compound indexes using multiple attributes, and unique indexes, which ensure that duplicate values are not allowed.
然而，由于xml列不属于表分区键的一部分，任何唯一xml值索引必须创建为全局索引。
However, since XML columns cannot be part of the table partitioning key, any unique XML values index will have to be created as a global index.
为每一行数据所创建的索引成为了计数器，因为每当新的一行数据加进来的时候，这个索引是唯一的增量，这也意味着计数器将与字符串数据的总量同步变化。
The index created for each row of data becomes the count because it was only incremented when a new row of data was found, meaning it is in sync with the amount of data in the string.
因为你已经确定我推断是三列以确定唯一性(主题行，主体和发件人地址)，所以您将创建包含所有三列的索引。
As you've identified what I infer to be three columns to determine uniqueness (subject line, body, and sender address) you'll create the index to include all three columns.
使用此对话框可以创建或修改索引、主键和唯一键。
Use this dialog box to create or modify indexes, primary keys, and unique keys.
使用此对话框可以创建或修改索引、主键和唯一键。
Use this dialog box to create or modify indexes, primary keys, and unique keys.
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