Returning distinct rows in SQLAlchemy with SQLite

Returning distinct rows in SQLAlchemy with SQLite

In SQLAlchemy, you can use the distinct method to return distinct rows from a query. When using SQLite as the backend, the syntax remains consistent with SQLAlchemy's ORM or Core.

Here's an example of how to use distinct in both the ORM and SQL Expression language:

Using SQLAlchemy ORM:

If you're using the ORM with declarative models, you would do something like this:

from sqlalchemy.orm import sessionmaker from your_application_model import YourModel, engine # Make sure to import your model and engine # Create a session Session = sessionmaker(bind=engine) session = Session() # Query distinct rows distinct_rows = session.query(YourModel.column_name).distinct().all() for row in distinct_rows: print(row)

Replace YourModel with your actual model class, and column_name with the field you want to be distinct.

Using SQLAlchemy Core:

For the SQL Expression language, the syntax is as follows:

from sqlalchemy import create_engine, MetaData, Table, select # Assume `engine` is your SQLite engine metadata = MetaData(bind=engine) # Reflect table your_table = Table('your_table', metadata, autoload_with=engine) # Select distinct rows query = select([your_table.c.column_name]).distinct() with engine.connect() as connection: result = connection.execute(query) for row in result: print(row)

Replace 'your_table' with your actual table name and column_name with the field you want to be distinct.

Note on Distinct on Multiple Columns:

If you want to select distinct rows based on all columns, you don't need to specify a column name:

# ORM distinct_rows = session.query(YourModel).distinct().all() # Core query = select([your_table]).distinct()

If you want to select distinct rows based on a combination of columns, you can pass multiple arguments to distinct:

# ORM distinct_rows = session.query(YourModel.column1, YourModel.column2).distinct().all() # Core query = select([your_table.c.column1, your_table.c.column2]).distinct()

Remember to replace column1 and column2 with the actual column names you're interested in. The distinct method will ensure that the combination of the values in these columns is unique for all rows returned.

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