NTH_VALUE
Value function. Returns an expression evaluated at the nth row of the window frame. If there are fewer than n rows in the frame, returns NULL
. For an overview of window functions in SingleStore DB, see Window Functions Guide.
Syntax
NTH_VALUE ( expression, n ) OVER ( [PARTITION BY (col | expr), ...] [ORDER BY (col | expr), ...] [frame_clause] )
Arguments
expression: any expression. This may be a column name, the result of another function, or a math operation.
n: an integer or integer expression.
Return Type
The result type of expression
Examples
create table example (a int, b int); insert into example values (1, 2), (2, 2), (3, 3), (4, 3); select a, nth_value(a, 2) over (order by a) from example; +------+-----------------------------------+ | a | nth_value(a, 2) over (order by a) | +------+-----------------------------------+ | 1 | NULL | | 2 | 2 | | 3 | 2 | | 4 | 2 | +------+-----------------------------------+ select a, nth_value(a, case when a > 2 then 1 else 2 end) over (order by a rows between unbounded preceding and unbounded following) as nth_value from example; +------+-----------+ | a | nth_value | +------+-----------+ | 1 | 2 | | 2 | 2 | | 3 | 1 | | 4 | 1 | +------+-----------+