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(Company.Id).label("CustomCount"), Company.Name).group_by(Company.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(Company_table.select().with_only_columns([func.count(Company_table.c.Id).label("CustomCount"), Company_table.c.Name])group_by(Company_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(Company.STCrAdjPercent).label("CustomSum"), Company.Name).group_by(Company.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(Company_table.select().with_only_columns([func.sum(Company_table.c.STCrAdjPercent).label("CustomSum"), Company_table.c.Name]).group_by(Company_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(Company.STCrAdjPercent).label("CustomAvg"), Company.Name).group_by(Company.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(Company_table.select().with_only_columns([func.avg(Company_table.c.STCrAdjPercent).label("CustomAvg"), Company_table.c.Name]).group_by(Company_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(Company.STCrAdjPercent).label("CustomMax"), func.min(Company.STCrAdjPercent).label("CustomMin"), Company.Name).group_by(Company.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(Company_table.select().with_only_columns([func.max(Company_table.c.STCrAdjPercent).label("CustomMax"), func.min(Company_table.c.STCrAdjPercent).label("CustomMin"), Company_table.c.Name]).group_by(Company_table.c.Name))
for instance in rs: