Ecto/Query

Ecto/Query

Ecto/Query is a powerful module in the Ecto library of the Elixir programming language. It provides a comprehensive set of tools for querying and manipulating databases in a functional and composable manner.

Basics of Ecto/Query

Ecto/Query allows developers to construct complex queries for retrieving data from a database using a concise and expressive syntax. The module provides a wide range of query operators and functions to filter, sort, aggregate, and join data.

Ecto/Query supports various types of queries, including simple queries, queries with conditions, ordering and pagination, associations, and aggregations. These different query types enable developers to efficiently retrieve the required data from the database.

Queries with Conditions

Ecto/Query allows developers to add conditions to their queries using operators such as `where`, `or_where`, `in`, `not_in`, `like`, `ilike`, and many more. These operators enable powerful filtering capabilities, allowing developers to retrieve only the desired data from the database.

Ordering and Pagination

With Ecto/Query, developers can easily specify the order in which the results should be returned using the `order_by` operator. Additionally, the module provides convenient functions like `offset` and `limit` for implementing pagination in queries.

Associations

Ecto/Query supports associations, which are relationships between tables in a database. Developers can use operators like `preload`, `join`, and `left_join` to query associated data efficiently. This enables the retrieval of related data without the need for multiple database calls.

Aggregations

Ecto/Query provides various functions for performing aggregations on data, such as `count`, `avg`, `min`, `max`, and `sum`. These functions can be used to calculate statistics or summarize data from the database.

Composable Queries

Ecto/Query allows developers to compose queries by chaining multiple operations together. This composability enables the construction of complex queries in a readable and maintainable manner.

Conclusion

Ecto/Query is a powerful module in the Ecto library of the Elixir programming language. Its expressive syntax, rich set of query operators, and support for associations make it an excellent tool for querying and manipulating databases. Whether you need to retrieve simple data or perform complex aggregations, Ecto/Query provides the necessary tools to efficiently interact with your database.

See Also

• Ecto
• Elixir Programming Language
• Ecto/Migrations
• Ecto/Schema
• Ecto/Changeset