The SQL SUM simply adds up all the value in a set of rows and return the result.
SUM operator only can use for column whish is content number only like Interger, Float, Double, etc.
The SQL SUM syntax is simple and looks like this:
SELECT SUM ( [COLUMN NAME] ) FROM [TABLE NAME]
We can see with a simple example which is return sum of the scores in the table.
SQL statement :
SELECT SUM(Scores) FROM GameScores