Glossary · Database

Aggregation

A SQL operation that computes a single result from a set of values, such as SUM, COUNT, AVG, MIN, or MAX.

Aggregation in SQL refers to operations that compute a single summary value from a set of input values. The standard aggregate functions are COUNT (number of rows), SUM (total of values), AVG (average), MIN (smallest value), and MAX (largest value). Aggregations are typically combined with GROUP BY to compute summaries per group (e.g., total revenue per department) and HAVING to filter groups based on aggregate values. Advanced aggregations include PERCENTILE_CONT, STRING_AGG, ARRAY_AGG, and user-defined aggregate functions. Window functions (OVER clause) provide aggregations across a "window" of rows related to the current row without collapsing the result set–enabling running totals, moving averages, and rankings.

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