runningDifference

Calculates the difference between successive row values ​​in the data block. Returns 0 for the first row and the difference from the previous row for each subsequent row.

Syntax

runningDifference(expression)

Arguments

Arguments	Description
expression	Any expression which generates numberic result, including integer numbers, real numbers, date and datetime.

Return Type

Numberic Type

Examples

databend :) DESC runing_difference_test;
┌─Field─┬─Type──┬─Null─┐
│ a     │ UInt8 │ NO   │
└───────┴───────┴──────┘

databend :) SELECT * FROM runing_difference_test;
┌──a─┐
│  1 │
│  3 │
│  5 │
│ 10 │
└────┘
┌──a─┐
│ 15 │
│ 20 │
└────┘

databend :) SELECT runningDifference(a) FROM runing_difference_test;
┌─runningDifference(a)─┐
│                    0 │
│                    2 │
│                    2 │
│                    5 │
└──────────────────────┘
┌─runningDifference(a)─┐
│                    0 │
│                    5 │
└──────────────────────┘