(1)
-- Table structure for stuscore
DROP TABLE IF EXISTS stuscore;
CREATE TABLE stuscore (
name varchar(20) DEFAULT NULL,
subject varchar(20) DEFAULT NULL,
score int(9) DEFAULT NULL,
stuid int(1) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- Records of stuscore
INSERT INTO stuscore VALUES ('张三', '语文', '81', '1');
INSERT INTO stuscore VALUES ('张三', '数学', '78', '1');
INSERT INTO stuscore VALUES ('张三', '物理', '77', '1');
INSERT INTO stuscore VALUES ('李四', '语文', '80', '2');
INSERT INTO stuscore VALUES ('李四', '数学', '91', '2');
INSERT INTO stuscore VALUES ('李四', '物理', '79', '2');
(2)
select t.name,sum(t.score) from stuscore t GROUP BY t.name
(3)
select t.name,t.score,t.subject from stuscore t ORDER BY t.score DESC LIMIT 0,2;
(4)
select t.name,sum(t.score)/COUNT(t.score) as temp_score from stuscore t GROUP BY t.name ORDER BY temp_score desc;