SELECT DISTINCT
중복제거
SELECT DISTINCT 컬럼명 FROM 테이블명;
SELECT COUNT (DISTINCT 컬럼명) FROM 테이블명;
Example
SELECT DISTINCT Country FROM Customers;
SELECT COUNT(DISTINCT Country) FROM Customers;
SELECT DISTINCT
중복제거
SELECT DISTINCT 컬럼명 FROM 테이블명;
SELECT COUNT (DISTINCT 컬럼명) FROM 테이블명;
SELECT DISTINCT Country FROM Customers;
SELECT COUNT(DISTINCT Country) FROM Customers;