W3Schools SQL | #13 SQL COUNT(), AVG(), SUM() 함수

SQL COUNT(), AVG() and SUM() Functions

The SQL COUNT(), AVG() and SUM() Functions

COUNT() Syntax

• 설정한 조건과 일치하는 행 수를 리턴한다.

  SELECT COUNT(column_name)
  FROM table_name
  WHERE condition;

AVG() Syntax

• 설정한 조건에 맞는 행 개수를 리턴한다.

  SELECT AVG(column_name)
  FROM table_name
  WHERE condition;

SUM() Syntax

• 설정한 조건에 맞는 행들의 지정한 열의 합 리턴

  SELECT SUM(column_name)
  FROM table_name
  WHERE condition;

DEMO Database

ProductID	ProductName	SupplierID	CategoryID	Unit	Price
1	Chais	1	1	10 boxes * 20 bags	18
2	Chang	1	1	24-12 oz bottles	19
3	Aniseed Syrup	1	2	12-550 ml bottles	10

COUNT() Example

SELECT COUNT(ProductID)
FROM Products;

AVG() Example

SELECT AVG(Price)
FROM Products;

SUM() Example

SELECT SUM(Quantity)
FROM OrderDetails;