这两者之间有明显的区别吗:
SELECT userid, username, userdept,
(SELECT deptname FROM depts WHERE deptid=userdept) AS deptname
FROM users
并且
SELECT userid, username FROM users
INNER JOIN depts ON depts.deptid=users.userdept
哪一个更好?
这两者之间有明显的区别吗:
SELECT userid, username, userdept,
(SELECT deptname FROM depts WHERE deptid=userdept) AS deptname
FROM users
并且
SELECT userid, username FROM users
INNER JOIN depts ON depts.deptid=users.userdept