当创建聚合查询时，适用某些逻辑原则。
When you create aggregate queries, certain logical principles apply.
下列原则描述如何在聚合查询的搜索条件中引用列。
The following principles describe how you can reference columns in an aggregate query in search conditions.
如果要创建小计或显示表的子集的其他汇总信息，可使用聚合查询创建组。
If you want to create subtotals or show other summary information for subsets of a table, you create groups using an aggregate query.
“分组依据”列(因为尚未指定聚合查询)，则搜索条件将被放入where子句中。
Group By column of the grid is not displayed (because you have not yet specified an aggregate query), the search condition is placed into the WHERE clause.
这让消费者不需要查询、访问多个数据源和执行聚合就可以得到自己想要的信息。
This allows the consumer to not have to query/access multiple data sources and perform the aggregation.
此场景的另一个副作用是数据库中的任何形式的实体化(预计算聚合)可能会被忽略，因为查询中不包含任何事实。
Another side effect to this scenario is that any form of materialization (pre-calculated aggregates) in the database may be ignored since no fact is included in the query.
数据库可以包含物化查询表（MQT），即用于 DWEOLAP模型和多维数据集的预联结和预聚合的表。
The database may contain materialized query tables (MQTs), the pre-joined and pre-aggregated tables for DWE OLAP models and cubes.
我发现有一个聚合索引成本的点 —例如，更为昂贵的INSERT和DELETE操作 —超出一个新索引的查询加速所能带来的效益。
We discovered that there is a point where aggregate index costs—more-expensive INSERT and DELETE operations, for example—outweigh a new index's query speed-up benefit.
模式4：对从其他供应商获得的服务聚合的查询。
Pattern 4: Inquiry with service aggregation acquired from another vendor.
MongoDB的查询引擎也使得对数据应用聚合和分组函数变得非常简单。
MongoDB's query engine also makes it very simple to apply aggregation and group functions on your data.
模式3：对聚合的辅助数据视图的查询。
MongoDB查询结果存储在提供过滤、聚合和排序等一系列功能的游标中，包括limit()、skip()、sort()、count()、distinct() 和group()。
MongoDB query results are stored in cursors that provide a range of functions for filtering, aggregation, and sorting including limit(), skip(), sort(), count(), distinct() and group().
MQT可用于通过预先计算聚合值来增强查询性能。
An MQT can be used to enhance query performance through the pre-computation of aggregate values. For example.
查询模型定义维度选择、边界、立方体视图以及维度数据的聚合与操纵等概念。
The query model defines the concepts of dimension selections, edges, cube views, and the aggregations and manipulations of dimensional data.
查询返回的数据聚合在多维数据集模型的一个切片上。
The query returns data aggregated at a single slice of the cube model.
来自多个来源的数据聚合：如果需要将来自多个服务调用和数据库查询等的结果合并成单个消息，则此模式非常有用。
Aggregation of data from multiple sources: This pattern is useful if the results from multiple service invocations, database lookups, and so on need to be combined into a single message.
本章中的很多查询都依赖于聚合的销售总额。
Many of the queries in this chapter rely on aggregated sales totals.
支持两种类型的查询：事件解决方案查询（它们只返回事件）和回答解决方案查询（它们可以返回任何非事件数据或聚合的结果）。
The two kinds of queries that are supported are: event solution queries, which return only events and the answer solution queries, which can return any non-event data or aggregated results.
OLAP查询通常将事实表的许多行聚合成一个相对少量的汇总结果。
OLAP queries typically aggregate many rows of the fact table into a relatively small number of summary results.
例如，该聚合器查询属性以显示合适的图标或替换文本。
For instance, the aggregator queries the attributes to display appropriate ICONS or alternate text.
先使用度量的聚合列表中的第一个聚合函数(在这个示例中是SUM)对表达式模板进行聚合，产生一个查询。
Start by generating the query using the first aggregation function (SUM in the example) in the measure's list of aggregations to aggregate the template expression.
因此，XGrind不能执行任何连接、聚合、嵌套查询或构建操作。
Therefore, XGrind cannot perform any join, aggregation, nested queries, or construct operations.
由于sales表存储每日销售总额，因此数据库设计应包括用于回答这些查询的聚合表。
Because the Sales table stores daily totals, your database design might include aggregate tables to answer these queries.
Nova服务查询公司BluePages服务器以获取请求的信息并聚合该信息。
The Nova service queries the corporate BluePages server for the requested information and aggregates it.
映射子查询和聚合功能
通过优化数据源提高OLAP系统的性能，文章详细介绍了优化数据库、聚合及采用记录客户查询的方法。
The paper introduces optimizing data sources to improve the performance of a OLAP system and the methods of optimizing database, aggregation and memorizing client record query.
介绍了在SQL中用聚合函数实现多表查询的一种方法。
This paper presents a method of query of tables by using aggregate function in SQL.
文章通过对聚合表技术的研究和分析，把该技术应用于基于ROLAP的数据挖掘中，既充分发挥了RO - LAP方法的优势，又克服了其查询效率低的最大弱点。
Though the research of aggregation table, and applied the techniques in data mining of ROLAP, not only fully displayed ROLAP superiority, but also overcome its biggest weakness of inquiry efficiency.
一个聪明的OLAP多维数据集将实现时，你应该使用一个聚合和重写你的查询，而不是使用汇总数据。
A smart OLAP cube will realize when you should use an aggregate and re-write your query to use the aggregated data instead.
以下部分列出了执行聚合运算的标准查询运算符方法。
The standard query operator methods that perform aggregation operations are listed in the following section.
应用推荐