Question

我想列出一个体育联盟中所有队员的名单，这些队员只有一名队员。

这是sql：

CREATE  TABLE `formsfiles`.`Teams` (
  `ID` INT NOT NULL AUTO_INCREMENT ,
  `Name` VARCHAR(45) NULL ,
  PRIMARY KEY (`ID`) );


INSERT INTO `Teams` (`Name`) VALUES ('Sharks');
INSERT INTO `Teams` (`Name`) VALUES ('Jets');
INSERT INTO `Teams` (`Name`) VALUES ('Fish');
INSERT INTO `Teams` (`Name`) VALUES ('Dodgers');
INSERT INTO `Teams` (`Name`) VALUES ('Pigs');

CREATE  TABLE `Players` (
  `ID` INT NOT NULL AUTO_INCREMENT ,
  `Name` VARCHAR(45) NULL ,
  `Team_ID` INT NULL ,
  PRIMARY KEY (`ID`) );

INSERT INTO `Players` (`Name`, `Team_ID`) VALUES ('Jim', '1');
INSERT INTO `Players` (`Name`, `Team_ID`) VALUES ('Tom', '1');
INSERT INTO `Players` (`Name`, `Team_ID`) VALUES ('Harry', '2');
INSERT INTO `Players` (`Name`, `Team_ID`) VALUES ('Dave', '2');
INSERT INTO `Players` (`Name`, `Team_ID`) VALUES ('Tim', '3');
INSERT INTO `Players` (`Name`, `Team_ID`) VALUES ('Trey', '4');
INSERT INTO `Players` (`Name`, `Team_ID`) VALUES ('Jay', '4');
INSERT INTO `Players` (`Name`, `Team_ID`) VALUES ('Steve', '4');
INSERT INTO `Players` (`Name`, `Team_ID`) VALUES ('Ziggy', '5');
INSERT INTO `Players` (`Name`, `Team_ID`) VALUES ('Chris', '4');

结果应该给我：

ID         Name
5          Tim
9          Ziggy

不确定如何将它们分组？

Answer 1

如果您想让只有一名成员的球队退回，您可以使用：

select p.id, p.name
from players p
where p.Team_ID in (select Team_ID
                    from players p
                    group by Team_ID
                    having count(Team_ID) = 1);

请参阅SQL Fiddle with Demo

编辑，您也可以使用（从评论中移动）：

select max(id) id, max(name) name
from players 
group by team_id
having count(team_id) = 1;

请参阅SQL Fiddle with Demo

Answer 2

谢谢Bluefeet：

这项工作很精彩：

我想在此处发布，以防将来有人宣传：

select max(id) id, max(name) name
from players 
group by team_id
having count(team_id) = 1;

获取记录列表

2 个答案: