Question

CREATE DATABASE E_volunteerSy;

USE E_volunteerSy;
CREATE TABLE Participate_In
(		V_ID INT(4) PRIMARY KEY,
		Ename	 CHAR(20),
		POINTS INT(255),
        AName CHAR(20)
);

INSERT INTO Participate_In
values 
(1001,'Name1',10,'A'),
(1002,'Name2',3,'A'),
(1003,'Name3',11,'B'),
(1004,'Name4',3,'B'),
(1005,'Name5',4,'B');

如何才能使返回AName A和AName B的最高点的查询更加正确。 AName意味着活动名称。

Answer 1

您可以使用MAX和GROUP BY

来使用以下内容

SELECT AName, MAX(POINTS) AS Points FROM Participate_In GROUP BY AName

演示： http://www.sqlfiddle.com/#!9/7b8ea6/1/0

Answer 2

此查询将显示所有活动的最高分

SELECT Aname, MAX(points) 
FROM Participate_In
GROUP BY Aname

Answer 3

这将为每个AName值选择最高记录点数

SELECT *
FROM (
    SELECT *, ROW_NUMBER() OVER(PARTITION BY AName ORDER BY  POINTS DESC) AS RowNum
    FROM Participate_In
) Sub 
WHERE RowNum = 1

对于每项活动，显示志愿者最高分数

3 个答案: