需要查询来计算SQL Server中的Previous数据

Question

我在SQL Server中有以下示例数据表

以下是我在消费栏中计算结果的预期结果

Answer 1

您需要的查询使用具有相同表格的联接：

SELECT KategoriID, ad, odendi, COUNT(odendi) 
FROM ogrenci INNER JOIN 
      taksit ON ogrenci.KategoriID = taksit.KategoriID 
WHERE odendi=0 
GROUP BY KategoriID

Answer 2

我在mysql中写了这个并且它有效，如果你需要它用于不同的dbms，请告诉我：fiddle

select t1.item, t1.mydate, t1.reading, 
       coalesce((t1.reading - t2.reading),0) as consumption
from mytable t1 left join
mytable t2
on t2.item = (select max(item) from
                 mytable where item < t1.item)
order by t1.item asc

注意：如果您的商品代码每次都不增加1，此代码也会起作用（例如，您有项目1,5,7,8，它将计算5 -1,7 - 5和8-7之间的差异< / p>

编辑：代码也适用于sql-server

Answer 3

SQL 2012 +：

CREATE TABLE #foobar (item INT, d DATE, reading INT);

INSERT INTO #foobar
        ( item, d, reading )
VALUES  
    (1, '2015-06-01', 10),
    (2, '2015-06-02', 20),
    (3, '2015-06-03', 25);

SELECT *, COALESCE(reading - LAG(reading) OVER (ORDER BY d), 0)
FROM #foobar