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# Data query

There are several types of data queries

* Raw data query
* Aggregate query
* Downsampling query
* Single point supplementary null query
* Latest data query
* Align by device query
* Group by fill query

In order to achieve the above kinds of queries, a basic query component for a single time series is designed in the IoTDB query engine, and on this basis, various query functions are implemented.

## Related documents

* [Query fundamentals](../DataQuery/QueryFundamentals.md)
* [Basic query components](../DataQuery/SeriesReader.md)
* [Raw data query](../DataQuery/RawDataQuery.md)
* [Aggregate query](../DataQuery/AggregationQuery.md)
* [Downsampling query](../DataQuery/GroupByQuery.md)
* [Recent timestamp query](../DataQuery/LastQuery.md)
* [Align by device query](../DataQuery/AlignByDeviceQuery.md)
* [Fill function](../DataQuery/FillFunction.md)
* [Group by fill query](../DataQuery/GroupByFillQuery.md)