Aggregate Functions

SQL · Methods reference

SQL · Methods reference

📋 Overview

Functions collapsing many rows to one value — used with GROUP BY or alone.

🔧 Methods

Common aggregates

Function	Description
`COUNT(*)` / `COUNT(col)` / `COUNT(DISTINCT col)`	Row or non-null counts
`SUM(expr)`	Numeric total
`AVG(expr)`	Mean — NULLs skipped
`MIN(expr)` / `MAX(expr)`	Minimum / maximum
`BOOL_AND` / `BOOL_OR` (PG)	Logical aggregate
`ARRAY_AGG(col)` (PG)	Collect to array
`STRING_AGG(col, sep)` (PG)	Join strings with separator
`GROUP_CONCAT(col)` (MySQL)	Concatenate grouped strings

💡 Examples

See parent topic notes for runnable snippets; this page is the complete method index.

⚠️ Pitfalls

Mutating methods return None in Python — do not chain sort() / reverse() expecting a new list.
Default JS sort() compares strings — pass (a,b) => a-b for numbers.
SQL function names differ by dialect — verify Postgres vs MySQL docs.
Django QuerySet.update() skips save() signals and auto auto_now fields on models.

Methods

SQL · Methods

Conditional & Cast Functions

SQL · Methods reference

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📋 Overview 🔧 Methods Common aggregates 💡 Examples ⚠️ Pitfalls 🔗 Related