SQL Aggregate Functions
As the Basic SQL Tutorial points out, SQL is excellent at aggregating data the way you might in a pivot table in Excel. You will use aggregate functions all the time, so it's important to get comfortable with them. The functions themselves are the same ones you will find in Excel or any other analytics program. We'll cover them individually in the next few lessons. Here's a quick preview:
COUNTcounts how many rows are in a particular column.
SUMadds together all the values in a particular column.
MAXreturn the lowest and highest values in a particular column, respectively.
AVGcalculates the average of a group of selected values.
The Basic SQL Tutorial also pointed out that arithmetic operators only perform operations across rows. Aggregate functions are used to perform operations across entire columns (which could include millions of rows of data or more).