How to get difference between two rows for a column field?
I have a table like this:
rowInt Value
2 23
3 45
17 10
9 0
....
The column rowInt values are integer but not in a sequence with same increament. I can use the following sql to list values by rowInt:
SELECT * FROM myTable ORDER BY rowInt;
This will list values by rowInt. How can get get the difference of Value between two rows with the result like this:
rowInt Value Diff
2 23 22 --45-23
3 45 -35 --10-45
9 0 -45 --0-45
17 10 10 -- 10-0
....
The table is in SQL 2005 (Miscrosoft)
Solution 1:
SELECT
[current].rowInt,
[current].Value,
ISNULL([next].Value, 0) - [current].Value
FROM
sourceTable AS [current]
LEFT JOIN
sourceTable AS [next]
ON [next].rowInt = (SELECT MIN(rowInt) FROM sourceTable WHERE rowInt > [current].rowInt)
EDIT:
Thinking about it, using a subquery in the select (ala Quassnoi's answer) may be more efficient. I would trial different versions, and look at the execution plans to see which would perform best on the size of data set that you have...
EDIT2:
I still see this garnering votes, though it's unlikely many people still use SQL Server 2005.
If you have access to Windowed Functions such as LEAD()
, then use that instead...
SELECT
RowInt,
Value,
LEAD(Value, 1, 0) OVER (ORDER BY RowInt) - Value
FROM
sourceTable
Solution 2:
SELECT rowInt, Value,
COALESCE(
(
SELECT TOP 1 Value
FROM myTable mi
WHERE mi.rowInt > m.rowInt
ORDER BY
rowInt
), 0) - Value AS diff
FROM myTable m
ORDER BY
rowInt