NTH_VALUE

Warning

SingleStore 9.0 gives you the opportunity to preview, evaluate, and provide feedback on new and upcoming features prior to their general availability. In the interim, SingleStore 8.9 is recommended for production workloads, which can later be upgraded to SingleStore 9.0.

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

SQL

CREATE TABLE nth_example (a int, b int);

INSERT INTO nth_example VALUES (1, 2), (2, 2), (3, 3), (4, 3);

SQL

SELECT a, NTH_VALUE(a, 2) OVER (ORDER BY a) FROM nth_example;

+------+-----------------------------------+
| a    | NTH_VALUE(a, 2) OVER (ORDER BY a) |
+------+-----------------------------------+
|    1 |                              NULL |
|    2 |                                 2 |
|    3 |                                 2 |
|    4 |                                 2 |
+------+-----------------------------------+

SQL

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 nth_example;

+------+-----------+
| a    | nth_value |
+------+-----------+
|    1 |         2 |
|    2 |         2 |
|    3 |         1 |
|    4 |         1 |
+------+-----------+