Question

Oracle11g的

我想知道玩家是否玩过游击手。但是，一个球员甚至可能不在我的桌子上，但我还是想为那个玩家返回一排。在这种情况下，玩家＃3不在桌子中，但我还是要返回一行。

选择标准

如果玩家至少有一个SHORTSTOP记录，那么只用YES返回1行。

如果玩家至少有一条记录而且没有一条是SHORTSTOP，那么只返回一行NO。

如果玩家没有记录，则只返回一行NO。

查询

with baseball_players as 
(select 1 as player_id, 'SHORTSTOP' as position  from dual union all
 select 1 as player_id, 'FIRSTBASE' as position  from dual union all
 select 2 as player_id, 'FIRSTBASE' as position  from dual)                                                  
select player_id,  case position 
   when 'SHORTSTOP' then 'YES' 
   else 'NO'
   end   has_played
from baseball_players 
where player_id in (1,2,3)

问题：如何编写查询以获得所需结果？

所需输出

PLAYER_ID  HAS_PLAYED
----------------------
   1        YES
   2        NO
   3        NO

Answer 1

不是使用where子句，而是创建一个临时表，在你创建的表中插入值和左连接。

对IF NULL使用case语句，然后使用NO，否则为YES。

Answer 2

这个怎么样：

WITH playerList AS
    (
        SELECT 
            1 player_id
        FROM 
            dual
        UNION
        SELECT 
            2
        FROM 
            dual
        UNION
        SELECT 
            3
        FROM 
            dual
    )
, baseball_players as 
    (
        select 1 as player_id, 'SHORTSTOP' as position  from dual union all
        select 1 as player_id, 'FIRSTBASE' as position  from dual union all
        select 2 as player_id, 'FIRSTBASE' as position  from dual 
    )
SELECT 
    pl.player_id
    , MAX(CASE WHEN bp.position = 'SHORTSTOP' THEN 'YES' ELSE 'NO' END)
FROM
    playerList pl
LEFT JOIN 
    baseball_players bp
    ON 
    bp.player_id = pl.player_id
GROUP BY 
    pl.player_id

如何为'where value in'子句中的每个项返回记录？

2 个答案: