Page 85 - SQL

Examples

SUM

Sum function sum the value of all the rows in the group. If the group by clause is omitted then sums
all the rows.

select sum(salary) TotalSalary
from employees;

TotalSalary

2500

select DepartmentId, sum(salary) TotalSalary
from employees
group by DepartmentId;

DepartmentId TotalSalary

1 2000

2 500

Conditional aggregation

Payments Table

Customer Payment_type Amount

Peter Credit 100

Peter Credit 300

John Credit 1000

John Debit 500

select customer,
sum(case when payment_type = 'credit' then amount else 0 end) as credit,
sum(case when payment_type = 'debit' then amount else 0 end) as debit
from payments
group by customer

Result:

https://riptutorial.com/ 67