Check out example codes for "sql group by sum". It will help you in understanding the concepts better.

Code Example 1

# Use SQL Group By clause after the Where clause
# Any column in the select list must either be in the Group By clause 
# or part of an agregation statement, like the Sum() statement
# Multiple columns can be included in the Group By Clause seperated by a comma
# Multiple columns stipulate the order tree. Order by 
# first column, then second ... etc

Select LastName, FirstName, Sum(LeaveDays), Max(age)
From EmployeeProjects
Where StartDate > '2020-01-01'
Group By LastName, FirstName

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