Question

首先，这是家庭作业，但我不是以任何方式寻找答案。我在数据库类中，我们获得了一个数据库，其中包含美国棒球联盟的统计数据（团队，每个人的统计数据等），每个表的模式定义都在问题的下方。我需要写的查询是：

同一支队伍中的哪一对击球手最多成为一对？您的查询应该提供对中每个击球手的名字和姓氏以及每个击球次数。

所以基本上，只需要按照每个团队的两个最高本垒打，看看哪个团队的金额最高，但我在编写一个查询时遇到问题，这个查询将产生每个团队中得分最高的人（就本垒打而言）。到目前为止我所拥有的是这样的。

select 
    nameFirst, nameLast, name, HR
from 
    Players, Teams, Batting
where 
    HR >= ALL(select HR from Batting) 
    and Players.playerID = Batting.playerID;

显示正确的团队名称（我知道这是因为它显示了30个元组，这就是数据库中的团队数量），但本垒打量和玩家的名字和姓氏都是相同的。（在这个数据库中，它是Brewers的Prince Fielders，因为他拥有数据库中最多的本垒打。）关于如何实现的提示是如此显示正确的人的名字和姓，非常感谢！

CREATE TABLE Players
(
    playerID VARCHAR(10), --A unique code asssigned to each player. The playerID
    --links the data in this file with records in the other files.
    nameFirst VARCHAR(50), --First name
    nameLast VARCHAR(50), --Last name
    bats CHAR(1), --Player's batting hand (left, right, or both)
    throws CHAR(1), --Player's throwing hand (left or right)
    PRIMARY KEY (playerID)
);

CREATE TABLE Teams
(
    teamID CHAR(3), --Three-letter team code
    lgID CHAR(2), --Two-letter league code
    divID CHAR(1), --One letter code for the division the team player in
    Rank SMALLINT, --Position in final standings in that division
    G SMALLINT, --Games played
    W SMALLINT, --Games won
    L SMALLINT, --Games lost
    DivWin CHAR(1), --Division winner (Y or N)
    WCWin CHAR(1), --Wild card winner (Y or N)
    LgWin CHAR(1), --League champion (Y or N)
    WSWin CHAR(1), --World series winner
    name VARCHAR(50), --Team's full name
    park VARCHAR(255), --Name of team's home ballpark
    PRIMARY KEY (teamID)
);

CREATE TABLE Batting
(
    playerID VARCHAR(10), --Player ID code
    yearID SMALLINT, --Will always be 2011 in data for this assignment
    stint SMALLINT, --Used to identify a particular continuous period that
    --a player played for one team during the season. For example, a player
    --who played during May for the Brewers, was then sent down to the
    --minors and came back to play again for the Brewers in August would
    --have two stints -- numbered 1 and 2
    teamID CHAR(3), --Three-letter team ID
    lgID CHAR(2), --Two letter league ID -- NL or AL
    G SMALLINT, --Number of games appeared in during this stint
    G_batting SMALLINT, --Number of games appeared in as a batter during this stint
    AB SMALLINT, --Number of at bats
    R SMALLINT, --Number of runs
    H SMALLINT, --Number of hits
    doubles SMALLINT, --Number of doubles
    triples SMALLINT, --Number of triples
    HR SMALLINT, --Number of home runs
    RBI SMALLINT, --Number of runs batted in
    SB SMALLINT, --Number of stolen bases
    CS SMALLINT, --Number of times caught trying to steal a base
    BB SMALLINT, --Number of base on balls (walks)
    SO SMALLINT, --Number of time player struck out
    IBB SMALLINT, --Number of intentional walks received
    HBP SMALLINT, --Number of time hit by pitch
    SF SMALLINT, --Number of sacrifice flied
    GIDP SMALLINT, --Number of times grounded into double play
    PRIMARY KEY (playerID, stint)
);

Answer 1

我假设HR在Batter表中，即使它似乎不在表定义中。但你需要做的是将击球手表连接到自己身上。您可以在同一查询中多次从同一个表中进行查询，只需为每个表实例提供不同的别名即可。

通过将Batter表连接到自身，您正在创建所谓的“笛卡尔积”，它基本上是该表中每两个击球员的组合。从那里，您可以计算HR的总和，然后相应地按该值排序。

如果你愿意，我会为你提供查询，但我知道你说这是家庭作业，所以如果你想根据我的解释想出来，你可以发布任何问题，我可以从那里得到帮助：）< / p> 祝你好运！

Answer 2

select t.teamname, p1.HR + p2.HR as [Sum], p1.playerid, p2.playerid
from player p1
join player p2
  on p1.teamid = p2.teamid
  and p1.playerid <> p2.playerid
join team t
  on p1.teamid = t.teamid
  and p2.teamid = t.teamid

这将使你走上正轨，希望如此。

查找每个团队拥有最高本垒打的人（DERBY / SQL）

2 个答案: