我在 APEX 應用程式的不同專案中有以下兩個查詢：
第 1 項：
SELECT SUM(t.gems)
FROM (SELECT gems
FROM tasks
UNION ALL
SELECT gems
FROM quests
UNION ALL
SELECT gems
FROM daily_quests
) t
第 2 項：
SELECT SUM(price) FROM items
它們都正確回傳了一個數字，但我想在一個陳述句中減去它們。我試著用
SELECT TO_NUMBER(ITEM1)-TO_NUMBER(ITEM2) FROM DUAL
但它沒有用。
你有什么建議嗎？我對 APEX 和 SQL 有點陌生。
先感謝您。
uj5u.com熱心網友回復：
對每個查詢使用 CTE（公用表運算式），然后是CROSS JOIN它們。
WITH t_gems (sum_gems) AS
(
SELECT SUM(t.gems)
FROM (SELECT gems
FROM tasks
UNION ALL
SELECT gems
FROM quests
UNION ALL
SELECT gems
FROM daily_quests
) t
), t_items (sum_price) AS
(
SELECT SUM(price) FROM items
)
SELECT t_gems.sum_gems - t_item.sum_price
FROM t_gems CROSS JOIN t_items
uj5u.com熱心網友回復：
假設每個查詢產生一個名為gems您可以執行的列：
with
a as (
-- query 1 here
),
b as (
-- query 2 here
)
select a.gems - b.gems as diff
from a
cross join b
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