SQL SUM Function

The SQL SUM function returns the total value within a table or group. In this section we’ll use the HumanResource.Employee table for our examples: 

Using the data above, SUM calculates the total SickLeaveHours for all employees:

SELECT SUM(sickleavehours) SUMSickLeaveHours 
  FROM HumanResources.Employee

When used with GROUP BY, SUM totals the values within a group. You can see this in this query showing the maximum SickLeaveHours by JobTitle:

SELECT JobTitle 
 , SUM(sickleavehours) AS SUMSickLeaveHours 
FROM HumanResources.Employee 
GROUP BY JobTitle 
ORDER BY JobTitle;

Additional SQL SUM Resources  

To learn more, check out these useful resources: 

• Summarize Your SQL Results with the GROUP BY clause 
• How to Calculate a Running Total 
• Recommended book SQL Practice Problems: 57 beginning, intermediate, and advanced challenges for you to solve using a “learn-by-doing” approach