SUM function in SQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the SQL SUM() function do?

The SUM() function adds up all the values in a numeric column and returns the total.

beginner

How do you use the SUM() function in a SQL query?

You write SELECT SUM(column_name) FROM table_name; to get the total of all values in that column.

intermediate

Can SUM() be used with GROUP BY? What does it do then?

Yes, SUM() can be used with GROUP BY to add values for each group separately.

intermediate

What happens if the column used in SUM() contains NULL values?

The SUM() function ignores NULL values and only adds the non-NULL numbers.

beginner

Is it possible to use SUM() on non-numeric columns?

No, SUM() only works on numeric columns like integers or decimals.

What does SELECT SUM(price) FROM sales; return?

A The total of all prices in the sales table

B The average price in the sales table

C The number of rows in the sales table

D The highest price in the sales table

The SUM() function adds all values in the price column.

If a column has NULL values, how does SUM() treat them?

A It treats NULL as zero

B It returns NULL as the result

C It ignores NULL values

D It causes an error

SUM() skips NULL values and sums only non-NULL numbers.

Which SQL clause is used with SUM() to get totals per category?

A GROUP BY

B WHERE

C ORDER BY

D HAVING

GROUP BY groups rows so SUM() totals each group.

Can you use SUM() on a text column?

A Yes, it converts text to numbers automatically

B No, it only works on numeric columns

C Yes, but only if text contains numbers

D Only in some SQL databases

SUM() requires numeric data types to work.

What will this query return? SELECT SUM(quantity) FROM orders WHERE quantity > 5;

A Maximum quantity in orders

B Sum of all quantities including those 5 or less

C Count of orders with quantity greater than 5

D Sum of quantities greater than 5

The WHERE clause filters rows before SUM() adds values.

Explain how the SUM() function works in SQL and give a simple example.

Think about adding numbers in a column.

Describe how you would use SUM() with GROUP BY to find totals per category.

Imagine adding sales per product type.