SQL 合并两个查询结果并求和 gold 值

可以使用子查询和 GROUP BY 语句来实现求和操作：

SELECT user_id, SUM(gold) as total_gold FROM (
	SELECT gold/1000 as gold,id as user_id FROM vp_user
	UNION
	SELECT SUM(si.price)*45/1000 as gold, create_user_id as user_id FROM economy.vp_user_inventory ui 
	JOIN economy.vp_steam_item as si ON ui.item_id = si.id 
    GROUP BY create_user_id
) AS result_table
GROUP BY user_id;

此代码将两个子查询的结果合并，并使用 SUM(gold) 函数对 gold 列进行求和，最终以 user_id 分组返回结果。