aggregate.ts — drizzle-orm Source File

Source Code

import { type AnyColumn, Column } from '~/column.ts';
import { is } from '~/entity.ts';
import { type SQL, sql, type SQLWrapper } from '../sql.ts';

/**
 * Returns the number of values in `expression`.
 *
 * ## Examples
 *
 * ```ts
 * // Number employees with null values
 * db.select({ value: count() }).from(employees)
 * // Number of employees where `name` is not null
 * db.select({ value: count(employees.name) }).from(employees)
 * ```
 *
 * @see countDistinct to get the number of non-duplicate values in `expression`
 */
export function count(expression?: SQLWrapper): SQL<number> {
	return sql`count(${expression || sql.raw('*')})`.mapWith(Number);
}

/**
 * Returns the number of non-duplicate values in `expression`.
 *
 * ## Examples
 *
 * ```ts
 * // Number of employees where `name` is distinct
 * db.select({ value: countDistinct(employees.name) }).from(employees)
 * ```
 *
 * @see count to get the number of values in `expression`, including duplicates
 */
export function countDistinct(expression: SQLWrapper): SQL<number> {
	return sql`count(distinct ${expression})`.mapWith(Number);
}

/**
 * Returns the average (arithmetic mean) of all non-null values in `expression`.
 *
 * ## Examples
 *
 * ```ts
 * // Average salary of an employee
 * db.select({ value: avg(employees.salary) }).from(employees)
 * ```
 *
 * @see avgDistinct to get the average of all non-null and non-duplicate values in `expression`
 */
export function avg(expression: SQLWrapper): SQL<string | null> {
	return sql`avg(${expression})`.mapWith(String);
}

/**
 * Returns the average (arithmetic mean) of all non-null and non-duplicate values in `expression`.
 *
 * ## Examples
 *
 * ```ts
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