# ABS, RMS, DIST
# 절대값, 제곱 평균 제곱근, 거리

DROP TABLE IF EXISTS location_1d;
CREATE TABLE location_1d (
    x1 integer
  , x2 integer
);

INSERT INTO location_1d
VALUES
    ( 5 , 10)
  , (10 ,  5)
  , (-2 ,  4)
  , ( 3 ,  3)
  , ( 0 ,  1)
;

DROP TABLE IF EXISTS location_2d;
CREATE TABLE location_2d (
    x1 integer
  , y1 integer
  , x2 integer
  , y2 integer
);

INSERT INTO location_2d
VALUES
    (0, 0, 2, 2)
  , (3, 5, 1, 2)
  , (5, 3, 2, 1)
;

## ABS, RMS
## 절대값 - abs, 제곱- power, 제곱근 - sqrt
select
	abs(x1-x2) AS abs
    , sqrt(power(x1-x2, 2)) AS rms
FROM location_1d
;

## Dist
## 유클리드 거리구하기
SELECT
	sqrt(power(x1-x2, 2)) + sqrt(power(y1-y2, 2)) AS dist
FROM location_2d
;

#위 내용은 SQL 레시피  (한빛미디어)를 참고하였습니다.