SQL連接以獲取字段名稱

Question

我有以下查詢，我希望編寫一個聯接，以根據ID給我提供股票趨勢的方向。

stock_trends
------------
stock_id
trend_id
direction_id
timestamp
price
breakout_price


trend_direction
---------------
id
direction


select s.*, v.latest_trend_date, 
dbo.GetStockAverageVolume(s.id, latest_trend_date, GETDATE()) 
as avg_volume from stocks s
join(select stock_id, MAX(timestamp)as latest_trend_date from stock_trends st
group by st.stock_id) v on v.stock_id = s.id
where 
(select top 1 trend_id from stock_trends 
where s.id = stock_trends.stock_id order by [timestamp] desc) = 
@trend_id and s.market_id = @market_id
and dbo.GetStockAverageVolume(s.id, latest_trend_date, GETDATE()) > 300000
order by latest_trend_date desc

如何修改上述查詢以根據stock_trends表中的direction_id獲取趨勢的方向？

例如：

select s.*, v.latest_trend_date, 
dbo.GetStockAverageVolume(s.id, latest_trend_date, GETDATE()) 
as avg_volume, **direction** from stock s
...
...
...

伙計，我不擅長加入！

非常感謝。

Answer 1

這應該可以，但是我認為您的查詢可以優化

 select stock_id, td.direction, MAX(timestamp) as latest_trend_date
 from stock_trends st
 join trend_direction td on st.direction_id = td.id
 group by st.stock_id, td.direction

是的，然后將v.direction添加到主列表中。