SQL編號大於選擇結果

Question

我正在努力想辦法用T-SQL做到這一點。

我有一個表格，該表格每5秒填充三種貨幣（GBP，EUR和USD）的價格

我創建了一個觸發器（插入后），該觸發器選擇為給定貨幣輸入的最后5條記錄：

SELECT TOP 5 Price from dbo.prices where coin='GBP' ORDER BY Date Desc

我想確定最后插入的貨幣價格是否大於上面選擇的5，我該怎么做？

謝謝

Answer 1

我猜想：一次不能有兩個輸入相同貨幣的條目。 每一段時間（5秒）每種貨幣只能插入一次。 因此，這應該符合您的要求：

declare @prices  table ([Date] int IDENTITY(1,1) primary key, Price float, coin varchar(3));  
insert into @prices  (coin, Price) values 
('GBP', 3.20),('EUR', 3.14),('USD', 3.14),
('GBP', 3.17),('EUR', 3.16),('USD', 3.11),
('GBP', 3.14),('EUR', 3.13),('USD', 3.16),
('GBP', 3.15),('EUR', 3.12),('USD', 3.17),
('GBP', 3.16),('EUR', 3.17),('USD', 3.11),
('GBP', 3.15),('EUR', 3.14),('USD', 3.12),
('GBP', 3.19),('EUR', 3.14),('USD', 3.16)

select
    case
        when NEW.Price > PREV.Price Then 'yes'
        else 'No'
    end as CURR_JUMP_UP
from
    (
        select top 1 COALESCE(Price,0) Price, [Date]
        from @prices where coin='GBP' order by [Date] desc
    ) NEW
    cross apply
    (
        select MAX(Price) Price from
        (
            select top 5 Price
            from @prices
            where coin='GBP' and [Date]<NEW.[Date]
            order by [Date] desc
        ) t
    ) PREV

Answer 2

試試這個查詢：

DECLARE @AmountLastFiveEntry DECIMAL= (SELECT TOP 5 SUM(Price) FROM dbo.prices WHERE 
    ID NOT IN (SELECT TOP 1 ID 
    FROM dbo.prices where coin='GBP' ORDER BY Date Desc) where coin='GBP' ORDER BY Date Desc)
     IF  @AmountLastFiveEntry<(SELECT TOP 1 Price 
    FROM dbo.prices where coin='GBP' ORDER BY Date Desc)
    BEGIN
    SELECT @AmountLastFiveEntry --To do task
    END

Answer 3

觸發部分令人困惑

這將報告最新價格是否高於（或等於）先前5個的最高價格。

declare @currency table (iden int IDENTITY(1,1) primary key, exchange smallint,  coin tinyint);  
insert into @currency (coin, exchange) values 
       (1, 1)
     , (1, 2)
     , (1, 3)
     , (1, 4)
     , (1, 5)
     , (1, 6)
     , (2, 1)
     , (2, 2)
     , (2, 3)
     , (2, 4)
     , (2, 5)
     , (2, 3);

select cccc.coin, cccc.exchange 
     , case when cccc.rn = cccc.rne then 'yes'
            else 'no'
       end  as 'high'
from ( select ccc.iden, ccc.coin, ccc.exchange, ccc.rn 
            , ROW_NUMBER() over (partition by ccc.coin order by ccc.exchange desc, ccc.rn) rne 
       from ( select cc.iden, cc.coin, cc.exchange, cc.rn  
              from ( select c.iden, c.coin, c.exchange 
                          , ROW_NUMBER() over (partition by coin order by iden desc) as rn
                     from @currency c
                   ) cc 
              where cc.rn <= 6 
            ) ccc
     ) cccc
where cccc.rn = 1
order by cccc.coin