Aggregate Functions
Certain aggregate functions can also be used within SQLAlchemy by using the func module. First, you will need to import it:
from sqlalchemy.sql import func
Once imported, the following aggregate functions are available:
COUNT
This example counts the number of records in a set of groups using the session object's query() method.
rs = session.query(func.count(Accounts.Id).label("CustomCount"), Accounts.Name).group_by(Accounts.Name) for instance in rs: print("Count: ", instance.CustomCount) print("Name: ", instance.Name) print("---------")
Alternatively, you can execute COUNT using the session object's execute() method.
rs = session.execute(Accounts_table.select().with_only_columns([func.count(Accounts_table.c.Id).label("CustomCount"), Accounts_table.c.Name])group_by(Accounts_table.c.Name)) for instance in rs:
SUM
This example calculates the cumulative amount of a numeric column in a set of groups.
rs = session.query(func.sum(Accounts.AnnualRevenue).label("CustomSum"), Accounts.Name).group_by(Accounts.Name) for instance in rs: print("Sum: ", instance.CustomSum) print("Name: ", instance.Name) print("---------")
Alternatively, you can invoke SUM using the session object's execute() method.
rs = session.execute(Accounts_table.select().with_only_columns([func.sum(Accounts_table.c.AnnualRevenue).label("CustomSum"), Accounts_table.c.Name]).group_by(Accounts_table.c.Name)) for instance in rs:
AVG
This example calculates the average amount of a numeric column in a set of groups using the session object's query() method.
rs = session.query(func.avg(Accounts.AnnualRevenue).label("CustomAvg"), Accounts.Name).group_by(Accounts.Name) for instance in rs: print("Avg: ", instance.CustomAvg) print("Name: ", instance.Name) print("---------")
Alternatively, you can invoke AVG using the session object's execute() method.
rs = session.execute(Accounts_table.select().with_only_columns([func.avg(Accounts_table.c.AnnualRevenue).label("CustomAvg"), Accounts_table.c.Name]).group_by(Accounts_table.c.Name)) for instance in rs:
MAX and MIN
This example finds the maximum value and minimum value of a numeric column in a set of groups.
rs = session.query(func.max(Accounts.AnnualRevenue).label("CustomMax"), func.min(Accounts.AnnualRevenue).label("CustomMin"), Accounts.Name).group_by(Accounts.Name) for instance in rs: print("Max: ", instance.CustomMax) print("Min: ", instance.CustomMin) print("Name: ", instance.Name) print("---------")
Alternatively, you can invoke MAX and MIN using the session object's execute() method.
rs = session.execute(Accounts_table.select().with_only_columns([func.max(Accounts_table.c.AnnualRevenue).label("CustomMax"), func.min(Accounts_table.c.AnnualRevenue).label("CustomMin"), Accounts_table.c.Name]).group_by(Accounts_table.c.Name)) for instance in rs: