如何区分两行?

I want to find the difference between two rows on the same column group by id

我想通过id找出同一列组中的两行之间的差异

ID Value1 Value2

a  500 200
b  300 200
a  100 300
b  300 400
....

Expected output

预期的输出

ID Value1 Value2

a  400 -100
b  0 -200
....

How to make a query for the above condition.

如何对上述条件进行查询。

4 个解决方案

#1

You can use following:

您可以使用:

SELECT
    ID,
    MAX(Value1) - MIN(Value1),
    MIN(Value2) - MAX(Value2)
FROM
    myTableName
GROUP BY
    ID

But there is one assumption: the second row has always greater Value1 and lower Value2 than first one.

但是有一个假设:第二行总是比第一行有更大的值1，更低的值2。

#2

You can try:

你可以尝试:

SELECT t1.ID, max(t2.VALUE1 - t1.VALUE1)
FROM TABLE1 t1
    left join TABLE1 t2 on t1.id = t2.id
group by t1.id

SQL FIDDLE DEMO:

SQL小提琴演示:

#3

This query will give a absolute difference between max value of ID and min value of same ID:

此查询将给出ID的最大值与相同ID的最小值之间的绝对值:

SELECT ID
, ABS(MAX(VALUE1) - MIN(VALUE1)) AS v1Diff
, ABS(MAX(VALUE2) - MIN(VALUE2)) AS v2Diff
FROM TABLE1
GROUP BY ID

Sql Fiidle

But if you want get a real difference(negative diff) then we need to know which row is first and which row is next. Then we can count difference like firstRowValue - nextRowValue.

但是如果你想要得到一个真实的差值(- diff)那么我们需要知道哪一行是第一行，哪一行是下一行。然后我们可以像firstRowValue - nextRowValue那样计算差异。

Maybe your table has some RowID or DateTime column from where we can ordering a rows from same ID. What column/columns are Primery Key in your table?

也许您的表有一些RowID或DateTime列，我们可以在其中从相同的ID排序行。

#4

Use option with CTE and ROW_NUMBER() ranking function

使用CTE和ROW_NUMBER()排序函数的选项

 ;WITH cte AS
 (
  SELECT ID, 
         CASE ROW_NUMBER() OVER(PARTITION BY ID ORDER BY 1/0) % 2
           WHEN 1 THEN Value1
           WHEN 0 THEN -1 * Value1 END AS Value1,
         CASE ROW_NUMBER() OVER(PARTITION BY ID ORDER BY 1/0) % 2
           WHEN 1 THEN Value2
           WHEN 0 THEN -1 * Value2 END AS Value2
  FROM dbo.test22
  )
  SELECT ID, SUM(Value1) AS Value1, SUM(Value2) AS Value2
  FROM cte
  GROUP BY ID

Demo on SQLFiddle

演示在SQLFiddle

#1