SQL SERVER如何联接2个表

Question

I have 2 tables,

Table 1 StockCard

OutletKey   ProductKey  Date          qty
101         ABC         01/01/2014    10
101         ABC         21/02/2014    5
101         ABC         31/03/2014    5
101         ABC         05/06/2014    2
101         ABC         20/10/2014    3
101         ABC         11/11/2014    4
101         ABC         12/12/2014    7
101         ABC         05/01/2015    8
101         ABC         03/02/2015    10

And the second table is stock_date

OutletKey    StockDate
101          05/04/2014
101          14/10/2014
101          10/01/2015

And I want the result like this

OutletKey    ProductKey   StockDate   TotalQty
101          ABC          10/01/2015  44

So I need to calculate total qty before last date of stockdate which is 10/01/2015

Thanks

EDIT: I am writing query like this but the result is not correct.

Select SC.outletkey ,SC.productkey ,SD.StockDate ,Sum(SC.qty) as totalqty
From StockCard SC 
Inner Join StockDate SD 
On SC.outletkey = SD.outletkey and SC.date < SD.stockdate 
Group by SC.outletkey ,SC.productkey ,SD.StockDate

Answer 1

For most RDBMSs, I would do it like this:

SELECT sc.OutletKey
    ,sc.ProductKey
    ,sd.LastStockDate AS StockDate
    ,SUM(sc.qty) AS TotalQty
FROM StockCard sc
INNER JOIN (
        SELECT OutletKey
            ,MAX(StockDate) AS LastStockDate
        FROM stock_date
        GROUP BY OutletKey
    ) sd
    ON  sd.OutletKey = sc.OutletKey
    AND sc.Date      < sd.LastStockDate
GROUP BY sc.OutletKey
    ,sc.ProductKey
    ,sd.LastStockDate

For SQL Server, I'd convert the INNER JOIN to a CROSS APPLY , which might perform better:

SELECT sc.OutletKey
    ,sc.ProductKey
    ,sd.LastStockDate AS StockDate
    ,SUM(sc.qty) AS TotalQty
FROM StockCard sc
CROSS APPLY (
        SELECT MAX(StockDate) AS LastStockDate
        FROM stock_date
        WHERE OutletKey = sc.OutletKey
    ) sd
WHERE sc.Date < sd.LastStockDate
GROUP BY sc.OutletKey
    ,sc.ProductKey
    ,sd.LastStockDate

I don't think it's possible to move the inequality to the correlation, so that's why it's in the WHERE clause.

Answer 2

This should do the trick

Select StockCard.OutletKey, StockCard.ProductKey, stock_date.StockDate, sum(StockCard.TotalQty) as TotalQty 
from StockCard
inner join stock_date on StockCard.OutletKey = stock_date.OutletKey
group by StockCard.OutletKey, StockCard.ProductKey, stock_date.StockDate

What this does... Selects the requested columns, with a sum of the quatity. Then joins the other table up. Your result will be the quantities grouped by ID , product , and date .

Answer 3

Try this, work OK? I had to make some assumptions based on what little info we have on the data structure. Change the IN into a NOT IN if you want everything before that date rather than on that date.

Feedback is welcome if it doesn't quite fit what you want.

SELECT sd.OutletKey, sd.ProductKey, sd.StockDate, SUM(sc.qty) AS TotalQty
FROM stock_date sd
INNER JOIN StockCard sc ON sd.OutletKey = sc.OutletKey
   AND sd.ProductKey= sc.ProductKey
   AND sd.StockDate= sc.StockDate
WHERE sd.StockDate IN (
   SELECT MAX(StockDate) FROM stock_date
)
GROUP BY sd.OutletKey, sd.ProductKey, sd.StockDate

Not tested... so if anyone sees a problem, feel free to edit!