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.
FIRST_
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Returns an expression evaluated at the first row of the window frame.
If there are no rows in the frame, returns NULL.
Syntax
FIRST_VALUE ( expression ) 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.
Return Type
The result type of expression
Examples
CREATE TABLE fv_example (a INT, b INT);INSERT INTO fv_example VALUES (1, 2), (2, 2), (3, 3), (4, 3);
CREATE TABLE tick_table(TIMESTAMP DATETIME(6), symbol VARCHAR(5), comp_name VARCHAR (30), price NUMERIC(18,4));INSERT INTO tick_table VALUES('2022-11-18 10:55:36.000000','STC','SomeTechCo', 100.00),('2022-11-18 10:55:37.000000','STC','SomeTechCo', 102.00),('2022-11-18 10:55:42.000000', 'STC', 'SomeTechCo', 105.00),('2022-11-18 10:55:48.000000', 'STC', 'SomeTechCo', 101.00),('2022-11-18 10:56:03.000000', 'STC', 'SomeTechCo', 99.00),('2022-11-18 10:55:42.000000', 'AME', 'ACME', 198.00),('2022-11-18 10:55:50.000000', 'AME', 'ACME', 208.00),('2022-11-18 10:55:52.000000', 'AME', 'ACME', 210.00),('2022-11-18 10:55:55.000000', 'AME', 'ACME', 211.00),('2022-11-18 10:55:52.000000', 'OCO', 'OnCallCo', 21.00),('2022-11-18 10:55:55.000000', 'OCO', 'OnCallCo', 22.00),('2022-11-18 10:55:57.000000', 'OCO', 'OnCallCo', 21.00),('2022-11-18 10:56:00.000000', 'OCO', 'OnCallCo', 23.00),('2022-11-18 10:56:03.000000', 'OCO', 'OnCallCo', 24.00);
Window Function
SELECT a, FIRST_VALUE(a) OVER(ORDER BY (a)) FROM fv_example;
+------+-----------------------------------+
| a | FIRST_VALUE(a) OVER(ORDER BY (a)) |
+------+-----------------------------------+
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
+------+-----------------------------------+SELECT TIMESTAMP, symbol, price, FIRST_VALUE(price) OVER(PARTITION BY symbol) FROM tick_table GROUP BY TIMESTAMP;
+----------------------------+--------+----------+------------------------------------------------+
| TIMESTAMP | symbol | price | FIRST_VALUE(price) OVER (PARTITION BY symbol) |
+----------------------------+--------+----------+------------------------------------------------+
| 2022-11-18 10:55:50.000000 | AME | 208.0000 | 208.0000 |
| 2022-11-18 10:55:55.000000 | AME | 211.0000 | 208.0000 |
| 2022-11-18 10:55:52.000000 | OCO | 21.0000 | 21.0000 |
| 2022-11-18 10:55:57.000000 | OCO | 21.0000 | 21.0000 |
| 2022-11-18 10:56:00.000000 | OCO | 23.0000 | 21.0000 |
| 2022-11-18 10:56:03.000000 | OCO | 24.0000 | 21.0000 |
| 2022-11-18 10:55:36.000000 | STC | 100.0000 | 100.0000 |
| 2022-11-18 10:55:48.000000 | STC | 101.0000 | 100.0000 |
| 2022-11-18 10:55:42.000000 | STC | 105.0000 | 100.0000 |
| 2022-11-18 10:55:37.000000 | STC | 102.0000 | 100.0000 |
+----------------------------+--------+----------+------------------------------------------------+Window Frame Clause
SELECT a, FIRST_VALUE(a) OVER(ORDER BY (a)ROWS between CURRENT ROW and UNBOUNDED FOLLOWING) FROM fv_example;
+------+---------------------------------------------------+
| a | FIRST_VALUE(a) OVER(ORDER BY (a) |
| | ROWS between CURRENT ROW and UNBOUNDED FOLLOWING) |
+------+---------------------------------------------------+
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 4 |
+------+---------------------------------------------------+Last modified: February 16, 2023