EXTRACT

EXTRACT(YEAR|MONTH|DAY|HOUR|MINUTE|SECOND FROM <datetime expression>|<interval expression>)

The EXTRACT function extracts one field from a DATE, TIME, TIMESTAMP or INTERVAL expression. Returns BIGINT for all fields other than SECOND. For SECOND it returns DECIMAL(5,3) and includes milliseconds.

Syntax

Examples

Function	Result
EXTRACT(DAY FROM INTERVAL '2 3:4:5.678' DAY TO SECOND)	2
EXTRACT(HOUR FROM INTERVAL '2 3:4:5.678' DAY TO SECOND)	3
EXTRACT(MINUTE FROM INTERVAL '2 3:4:5.678' DAY TO SECOND)	4
EXTRACT(SECOND FROM INTERVAL '2 3:4:5.678' DAY TO SECOND)	5.678
EXTRACT(MINUTE FROM CURRENT_ROW_TIMESTAMP) where CURRENT_ROW_TIMESTAMP is 2016-09-23 04:29:26.234	29
EXTRACT (HOUR FROM CURRENT_ROW_TIMESTAMP) where CURRENT_ROW_TIMESTAMP is 2016-09-23 04:29:26.234	4

Use in Function

EXTRACT can be used for conditioning data, as in the following function which returns a 30 minute floor when CURRENT_ROW_TIMESTAMP is input for p_time.

CREATE or replace FUNCTION FLOOR30MIN( p_time TIMESTAMP )
RETURNS  TIMESTAMP
CONTAINS SQL
RETURNS NULL ON NULL INPUT
RETURN  floor(p_time to HOUR) + (( EXTRACT (  MINUTE FROM p_time  ) / 30)* INTERVAL '30' MINUTE ) ;

You would implement this function using code along the following lines:

SELECT stream FLOOR30MIN( CURRENT_ROW_TIMESTAMP ) as ROWTIME , * from "MyStream" ) over (range current row ) as r

Note

The code above assumes that you have previously created a stream called "MyStream."