Question

我有3个表我正在尝试加入内连接，但由于某种原因，它们会导致一堆重复的结果。我一直在试图弄清楚我的头发出了什么问题。以下是我正在使用的表格：

 Table:gameday.atbats

   GameName                     Inning num  b   s   o   Batter   Pitcher      Result
-----------------------------------------------------------------------------------------
    gid_2008_09_24_cinmlb_houmlb_1  1   1   2   3   1   457803  150116  Jay Bruce strikes out swinging.  
    gid_2008_09_24_cinmlb_houmlb_1  1   2   1   0   2   433898  150116  Jeff Keppinger lines out to right fielder Hunter Pence.  
    gid_2008_09_24_cinmlb_houmlb_1  1   3   3   1   2   458015  150116  Joey Votto singles on a line drive to right fielder Hunter Pence.  
    gid_2008_09_24_cinmlb_houmlb_1  1   4   2   3   3   429665  150116  Edwin Encarnacion called out on strikes.  
    gid_2008_09_24_cinmlb_houmlb_1  1   5   1   2   0   430565  459371  Kazuo Matsui singles on a line drive to right fielder Jay Bruce.  
-----------------------------------------------------------------------------------------

Table: Gameday.pitches
 GameName                   GameAtBatID      Result
------------------------------------------------------
gid_2008_09_24_cinmlb_houmlb_1  1       Called Strike
gid_2008_09_24_cinmlb_houmlb_1  1       Ball
gid_2008_09_24_cinmlb_houmlb_1  1       Swinging Strike
gid_2008_09_24_cinmlb_houmlb_1  1       Ball
gid_2008_09_24_cinmlb_houmlb_1  1       Foul
gid_2008_09_24_cinmlb_houmlb_1  1       Foul
gid_2008_09_24_cinmlb_houmlb_1  1       Swinging Strike
gid_2008_09_24_cinmlb_houmlb_1  2       Ball
gid_2008_09_24_cinmlb_houmlb_1  2       In play, out(s)
gid_2008_09_24_cinmlb_houmlb_1  3       Called Strike
gid_2008_09_24_cinmlb_houmlb_1  3       Ball
--------------------------------------------------------

Table:batters
   GameName                     id         name_display_first_last
----------------------------------------------------------------------------------
gid_2008_09_24_cinmlb_houmlb_1  407783      Geoff Geary
gid_2008_09_24_cinmlb_houmlb_1  209315      David Newhan
gid_2008_09_24_cinmlb_houmlb_1  115629      LaTroy Hawkins
gid_2008_09_24_cinmlb_houmlb_1  113889      Darin Erstad
gid_2008_09_24_cinmlb_houmlb_1  457803      Jay Bruce
gid_2008_09_24_cinmlb_houmlb_1  433898      Jeff Keppinger
gid_2008_09_24_cinmlb_houmlb_1  458015      Joey Votto
gid_2008_09_24_cinmlb_houmlb_1  429665      Edwin Encarnacion
---------------------------------------------------------------------------

我正在使用的代码如下：

    SELECT gameday.atbats.event
         , gameday.atbats.inning
         , gameday.batters.name_display_first_last
         , gameday.pitchers.name_display_first_last
         , gameday.pitches.result
      FROM gameday.atbats
inner join gameday.pitches on gameday.atbats.num = gameday.pitches.gameAtBatID
                          and gameday.pitches.gamename=gameday.atbats.gamename
inner join gameday.batters on gameday.atbats.batter = gameday.batters.ID
                          AND gameday.atbats.gamename = gameday.batters.gameName
     where gameday.atbats.gamename = "gid_2008_09_24_cinmlb_houmlb_1"

当前代码导致每个玩家的结果加倍，例如，如果游戏中的第一个击球手击出3个球场，则当前代码将输出该击球手在第一局中以6个球场击出两次。我加入了游戏ID和每张桌子的ID，但似乎仍然存在某种问题

Answer 1

没有冒犯，但我不喜欢＆＃34;使用不同的＆＃34;回答是因为它只会掩盖问题。在这种情况下我做的是在SELECT COUNT(*)正上方插入FROM行，然后逐步查看结果，一次添加一行;即，SELECT COUNT(*) FROM A，然后A JOIN B，然后是A JOIN B JOIN C等，以检测有问题的JOIN。

Answer 2

在你的查询中在最后一行，你已经用游戏名称写了where条件，所以游戏名称是唯一的，如果不是那么你会得到多个答案，所以更好的方法在gameday.atbats的条件下使用主键表

内部联接产生的重复数据

2 个答案: