How Can I Use SQLAlchemy's VALUES Clause to Create a SELECT Query for Multiple Rows?

Implementing the VALUES Clause with SQLAlchemy

In SQLAlchemy, the VALUES clause is commonly used with INSERT statements to insert multiple rows. However, it is not immediately apparent within the documentation how to create a Query object that produces a similar result.

Building the Query Object

To construct a Query object equivalent to the SQL statement SELECT * FROM (VALUES (1, 2, 3)) AS sq, we can utilize the Values clause in SQLAlchemy. The resulting query will be written as follows:

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

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

Explanation

1. Values Constructor: Values is a constructor that creates an object representing the VALUES clause. In this instance, it contains a single column named 'Number' with type Integer and named 'sq'.
2. data Method: The data method populates the Values object with a list of tuples, where each tuple represents a row of data.
3. select Function: The select function is used to construct a Query object that selects the contents of the Values object.

Note

While documentation on this specific usage of the VALUES clause is lacking, you can explore the test cases provided in the SQLAlchemy GitHub repository: https://github.com/sqlalchemy/sqlalchemy/blob/master/test/sql/test_values.py.

The above is the detailed content of How Can I Use SQLAlchemy's VALUES Clause to Create a SELECT Query for Multiple Rows?. For more information, please follow other related articles on the PHP Chinese website!