UNION：求两个或多个集合的并集，去除重复
UNION ALL：求两个或多个集合的并集，不去除重复
INTERSECT：求两个或多个集合的交集，去除重复
MINUS：求两个或多个集合的差集，去除重复
2023-07-16 09:34
166
0
0
0
SELECT * FROM student WHERE MONTH(birthday) = MONTH(DATE_ADD(NOW(), INTERVAL 1 MONTH));
2023-07-16 09:34
169
0
0
0
select distinct student_id
from student_course
group by student_id
having count(*) >= 2;
2023-07-16 09:34
143
0
0
0
MySQL 和 MongoDB 是两种不同的关系型和非关系型数据库管理系统（RDBMS 和 NoSQL）。
MySQL 是一种关系型数据库管理系统，它依赖于表的概念来组织数据，使用 Structured Que
2023-07-15 08:49
141
0
0
0
SELECT t1.name, t1.grade
FROM table1 t1
INNER JOIN
(
SELECT class, MAX(grade) AS max_grade
FRO
2023-07-15 08:48
143
0
0
0
SELECT s.name, g.score
FROM student AS s
INNER JOIN grade AS g ON s.id = g.student_id
INNER JOIN course
2023-07-15 08:48
156
0
0
0
SELECT sno,AVG(score)
FROM student
WHERE score < 60
GROUP BY sno
HAVING COUNT(score)>=2;
2023-07-14 09:07
151
0
0
0