Aggregate Functions
Compute a single value from many rows.
Questions this answers
- →How do I count the total number of rows?
- →How do I find the average, sum, min, or max?
- →How do I count only distinct values?
- →How do aggregates handle NULLs?
How it works
Aggregate functions collapse multiple rows into one value. COUNT, SUM, AVG, MIN, MAX — each takes a column and returns a single number. On their own (without GROUP BY) they operate on the entire table.
The five core aggregates
SELECT COUNT(*) AS total_rows, COUNT(label) AS with_label, AVG(monthly_listeners) AS avg_listeners, SUM(monthly_listeners) AS total_listeners, MIN(monthly_listeners) AS min_listeners, MAX(monthly_listeners) AS max_listeners FROM artists;
Count distinct values
SELECT COUNT(DISTINCT genre) AS unique_genres FROM artists;
💡 COUNT(DISTINCT col) counts unique non-NULL values.
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