
# Querying data

Understand how to query, search, and aggregate Redis data

Redis Open Source distinguishes between the [FT.SEARCH](/docs/latest/commands/ft.search/) and [FT.AGGREGATE](/docs/latest/commands/ft.aggregate/) query commands. You should use [FT.SEARCH](/docs/latest/commands/ft.search/) if you want to perform selections and projections only. If you also need to apply mapping functions, group, or aggregate data, use the [FT.AGGREGATE](/docs/latest/commands/ft.aggregate/) command.

*   **Selection**: A selection allows you to return all documents that fulfill specific criteria.
*   **Projection**: Projections are used to return specific fields of the result set. You can also map/project to calculated field values.
*   **Aggregation**: Aggregations collect and summarize data across several fields.

Here is a short SQL comparison using the [bicycle dataset](./data/bicycles.txt):

Type

SQL

Redis

Selection

`SELECT * FROM bicycles WHERE price >= 1000`

`FT.SEARCH idx:bicycle "@price:[1000 +inf]"`

Simple projection

`SELECT id, price FROM bicycles`

`FT.SEARCH idx:bicycle "*" RETURN 2 __key, price`

Calculated projection

`SELECT id, price-price*0.1 AS discounted FROM bicycles`

`FT.AGGREGATE idx:bicycle "*" LOAD 2 __key price APPLY "@price-@price*0.1" AS discounted`

Aggregation

`SELECT condition, AVG(price) AS avg_price FROM bicycles GROUP BY condition`

`FT.AGGREGATE idx:bicycle "*" GROUPBY 1 @condition REDUCE AVG 1 @price AS avg_price`

The following articles provide an overview of how to query data with the [FT.SEARCH](/docs/latest/commands/ft.search/) command:

*   [Exact match queries](exact-match/index.md)
*   [Range queries](range/index.md)
*   [Full-text search](full-text/index.md)
*   [Geospatial queries](geo-spatial/index.md)
*   [Vector search](vector-search/index.md)
*   [Combined queries](combined/index.md)

You can find further details about aggregation queries with [FT.AGGREGATE](/docs/latest/commands/ft.aggregate/) in the following article:

*   [Aggregation queries](aggregation/index.md)
