However, in SQL you can only perform arithmetic across columns on values in a given row. To clarify, you can only add values in multiple columns from the same row together using +—if you want to add values across multiple rows, you'll need to use aggregate functions, which are covered in the Intermediate SQL section of this tutorial.

Sure, I can help with that. In SQL, you can perform arithmetic operations like addition, subtraction, multiplication, and division on values within the same row of different columns. For example, if you have a table with columns 'A' and 'B', you can add the values of 'A' and 'B' in the same row together using the '+' operator.

However, if you want to perform arithmetic operations on values across multiple rows, you need to use aggregate functions. Aggregate functions allow you to perform calculations on a set of values and return a single value. Some examples of aggregate functions are SUM(), AVG(), MAX(), MIN(), and COUNT().

For instance, if you want to add all values in a column, you would use the SUM() function. If you want to find the average of all values in a column, you would use the AVG() function.

These aggregate functions are covered in more detail in the Intermediate SQL section of the tutorial.