How Can I Simulate a VALUES Clause in SQLAlchemy?

VALUES Clause in SQLAlchemy

When working with relational databases, the VALUES clause is often used to define a temporary table or "inline" data source within a query. This can be useful in various scenarios, such as combining data from multiple sources or creating a temporary dataset for analysis.

In SQLAlchemy, the VALUES clause is not natively supported in the same way as in direct SQL queries. However, there is a workaround that allows you to achieve the equivalent functionality using SQLAlchemy's Core API.

Building a Query with the VALUES Clause

To create a SQLAlchemy query that replicates the functionality of the given SQL statement:

SELECT * FROM (VALUES (1, 2, 3)) AS sq;

You can use the following code:

from sqlalchemy import select, column, Integer
from sqlalchemy.sql import Values

query = select(Values(column('Number', Integer), name='sq').data([(1,), (2,), (3,)]))

In this code:

• Values is a SQLAlchemy Core class that represents a table-valued expression using named columns.
• data method of the Values object is used to populate the inline data.
• The Number column is defined as an Integer type.
• The inline source is named sq using the name argument.

By executing this query, you will get a result set that contains three rows, each with a single column named Number containing the values 1, 2, and 3, respectively. It is important to note that the VALUES clause is not widely documented in SQLAlchemy's official documentation. However, you can refer to the test cases at https://github.com/sqlalchemy/sqlalchemy/blob/master/test/sql/test_values.py for further insights.

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