MySQL join, inner join

Reviews 테이블

UserID	UserName	ResID	Rating	RevSatis	RevRecom	RevTime
10	솜사탕	18	3.7	1	1	2023-05-23 05:19:59
7	탕후루	18	4.8	1	1	2023-05-21 21:59:17

Users 테이블

UserID	UserPhone	UserPW	UserGender	UserBirth	UserName
7	010-5555-5555	pw	M	1995-10-13	탕후루
10	010-0000-0000	pw	F	2000-01-01	솜사탕

SELECT UserGender FROM Users INNER JOIN Reviews ON Users.UserID = Reviews.UserID WHERE ResID=18 AND RevSatis=1;

UserGender
F
M

SELECT UserGender FROM Users JOIN Reviews ON Users.UserID = Reviews.UserID WHERE ResID=18 AND RevSatis=1;

UserGender
F
M

F,M으로 이루어진 행이 해당하는 ResID select 개수만큼 생긴다.