我想查询哪里我计算两列之间的差异。喜欢的东西:在别名上使用聚合函数?
SELECT a,
b,
a - b as "diff"
FROM ...
现在我想计算“差异”一栏的使用内置的STDDEV聚合函数PostgreSQL中STDDEV。我怎样才能做到这一点?
谢谢。
编辑:
的实际查询是这样的:
SELECT tr.date_start,
tr.date_end,
(((CASE when(tourney_summary.val_curr_conv != 0) THEN tourney_summary.val_curr_conv * (tr.amt_won + tr.cnt_bounty * tourney_summary.amt_bounty) ELSE 0.0 END))) AS "amt_won_curr_conv",
(((CASE when(tourney_summary.val_curr_conv != 0) THEN tourney_summary.val_curr_conv * (tourney_summary.amt_buyin + tourney_summary.amt_fee + tourney_summary.amt_rebuy * tr.cnt_rebuy + tourney_summary.amt_addon * tr.cnt_addon + tourney_summary.amt_bounty) ELSE 0.0 END))) AS "amt_buyin_ttl_curr_conv",
((((CASE when(tourney_summary.val_curr_conv != 0) THEN tourney_summary.val_curr_conv * (tr.amt_won + tr.cnt_bounty * tourney_summary.amt_bounty) ELSE 0.0 END))) - (((CASE when(tourney_summary.val_curr_conv != 0) THEN tourney_summary.val_curr_conv * (tourney_summary.amt_buyin + tourney_summary.amt_fee + tourney_summary.amt_rebuy * tr.cnt_rebuy + tourney_summary.amt_addon * tr.cnt_addon + tourney_summary.amt_bounty) ELSE 0.0 END)))) as net_amt_won,
stddev((((CASE when(tourney_summary.val_curr_conv != 0) THEN tourney_summary.val_curr_conv * (tr.amt_won + tr.cnt_bounty * tourney_summary.amt_bounty) ELSE 0.0 END))) - (((CASE when(tourney_summary.val_curr_conv != 0) THEN tourney_summary.val_curr_conv * (tourney_summary.amt_buyin + tourney_summary.amt_fee + tourney_summary.amt_rebuy * tr.cnt_rebuy + tourney_summary.amt_addon * tr.cnt_addon + tourney_summary.amt_bounty) ELSE 0.0 END)))) as diff_std_dev
FROM tourney_summary,
tourney_results tr
WHERE
tr.id_player=1
AND tourney_summary.id_tourney = tr.id_tourney
AND ((tourney_summary.id_gametype = 1)
AND (((((((tourney_summary.id_table_type IN
(SELECT lttt.id_table_type
FROM tourney_table_type lttt
WHERE lttt.val_seats = 2))))))
AND (((((tourney_summary.id_table_type IN
(SELECT lttt.id_table_type
FROM tourney_table_type lttt
WHERE position('S' IN lttt.val_speed) > 0))
OR (tourney_summary.id_table_type IN
(SELECT lttt.id_table_type
FROM tourney_table_type lttt
WHERE position('H' IN lttt.val_speed) > 0))))))))
AND ((tourney_summary.date_start >= '2013/08/15 23:00:00')))
GROUP BY tr.date_start,
tr.date_end,
tourney_summary.val_curr_conv,
tr.amt_won,
tr.cnt_bounty,
tourney_summary.amt_bounty,
tourney_summary.amt_buyin,
tourney_summary.amt_fee,
tourney_summary.amt_rebuy,
tr.cnt_rebuy,
tourney_summary.amt_addon,
tr.cnt_addon
ORDER BY tr.date_end DESC;
的 “A” 和 “B” 的表达式(CASE用的那些)都大。而且我不知道如何避免复制/粘贴。在任何情况下,在a-b表达式上使用stddev都会返回一个空白列。我究竟做错了什么?
谢谢。
注意你不需要大部分'(...)'括号(是由ORM生成此查询?)另外:你可以结合三个IN(...)子查询合并为一个(可能使用'EXISTS(...)'代替) – wildplasser
我认为查询可能是半自动生成的。 – dmz73