COUNT, SUM, AVG, MIN, MAX

GROUP BY Fundamentals

HAVING Clause

Compare COUNT(*) vs COUNT(column) on a table with NULL values

Build two AVG calculations: one ignoring NULL and one treating NULL as 0

Test SUM and AVG with a column where all values are NULL

Write a data quality query using COUNT differences

How does AVG handle NULL values?

What happens when all values are NULL?

When should you use COALESCE with aggregates?

GROUP BY Fundamentals

HAVING Clause

COALESCE and NULL handling