Starting here? This lesson is part of a full-length tutorial in using SQL for Data Analysis. Check out the beginning.
The SQL SUM function
SUM is a SQL aggregate function that totals the values in a given column. Unlike
COUNT, you can only use
SUM on columns containing numerical values.
The query below selects the sum of the
volume column from the Apple stock prices dataset:
An important thing to remember: aggregators only aggregate vertically. If you want to perform a calculation across rows, you would do this with simple arithmetic.
You don’t need to worry as much about the presence of nulls with
SUM as you would with
SUM treats nulls as 0.
Sharpen your SQL skills
Write a query to calculate the average opening price (hint: you will need to use both
SUM, as well as some simple arithmetic.).