Implementing sum and order by in SQLAlchemy
Writing an orderby function before a groupby function has a slightly different procedure than that of a conventional SQL query which is shown below
sqlalchemy.select([
Tablename.c.column_name,
sqlalchemy.func.sum(Tablename.c.column_name)
]).order_by(Tablename.c.column_name).group_by(Tablename.c.column_name)
Get the books table from the Metadata object initialized while connecting to the database. Pass the SQL query to the execute() function and get all the results using fetchall() function. Use a for loop to iterate through the results. The SQLAlchemy query shown in the below code groups the book by genre, then order the books alphabetically based on genre and return the sum of sales for each genre.
Python3
# Get the `books` table from the Metadata objectBOOKS = meta.tables['books']# SQLAlchemy Query to ORDER BY and GROUP BY query = sqlalchemy.select([ BOOKS.c.genre, sqlalchemy.func.sum(BOOKS.c.book_price)]).order_by(BOOKS.c.genre).group_by(BOOKS.c.genre)# Fetch all the recordsresult = engine.execute(query).fetchall()# View the recordsfor record in result: print("\n", record) |
Output:
Orderby before group by query result
SQLAlchemy – Order By before Group By
In this article, we are going to see how to perform the orderby function before using a groupby function in SQLAlchemy against a PostgreSQL database in Python.
PostgreSQL, Group by is performed using a function called groupby(), and order by the operation is performed using orderby().
Usage: func.sum(). func.group_by(), func.sum(), func.order_by()