How do you calculate the sum of two or more columns in MySQL?

In MySQL, summing two or more columns can be achieved by using the SUM() function and the + operator. Here are several steps and examples to illustrate how to do this:

Step 1: Identify the Columns to Sum

First, identify which columns need to be summed. For example, suppose we have a table called orders with two columns: price and tax.

Step 2: Use the SUM() Function for Single Column Sum

If you only need to sum one column, you can directly use the SUM() function. For example:

sql
SELECT SUM(price) AS total_price FROM orders;

This returns the sum of all values in the price column.

Step 3: Use the + Operator for Summing Multiple Columns

If you need to add the values of two or more columns together, use the + operator within the SELECT statement. For example, to calculate the sum of price and tax:

sql
SELECT SUM(price + tax) AS total_revenue FROM orders;

This statement adds price and tax for each row and then computes the sum of these values.

Example: Summing Multiple Columns

Suppose the orders table includes an additional shipping_cost column, and you want to calculate the sum of price, tax, and shipping_cost. The query would be:

sql
SELECT SUM(price + tax + shipping_cost) AS total_cost FROM orders;

Important Notes

• When using the SUM function, ensure column data types are compatible, typically integers or floating-point numbers.
• If a column contains NULL values, SUM() automatically ignores them. However, if all rows in the relevant column are NULL, the result will be NULL.

This covers the basic methods and steps for calculating the sum of two or more columns in MySQL. By following these examples, you can adjust the query statements to meet your specific requirements.