Subtract days from a date using DATE_SUB - Realtime Compute for Apache Flink

Subtracts a specified number of days from a date and returns the result as a DATE value.

Limitations

Requires Ververica Runtime (VVR) 3.0.0 or later in Realtime Compute for Apache Flink.

DATE DATE_SUB(VARCHAR startdate, INT days)
DATE DATE_SUB(TIMESTAMP time, INT days)

Parameter	Data type	Description
`startdate`	VARCHAR	The start date. Accepted formats: `yyyy-MM-dd` and `yyyy-MM-dd HH:mm:ss`.
`time`	TIMESTAMP	The start timestamp.
`days`	INT	The number of days to subtract.

Note If any input parameter is NULL or a parsing error occurs, the function returns NULL.

The following example subtracts 30 days from three different inputs: a VARCHAR date column, a TIMESTAMP literal, and a NULL value.

Test data

date1 (VARCHAR)	nullstr (VARCHAR)
2017-10-15	NULL

Test statement

SELECT DATE_SUB(date1, 30) AS var1,
       DATE_SUB(TIMESTAMP '2017-10-15 23:00:00', 30) AS var2,
       DATE_SUB(nullstr, 30) AS var3
FROM T1;

Result

var1 (DATE)	var2 (DATE)	var3 (DATE)
2017-09-15	2017-09-15	NULL

Both date1 (a VARCHAR date) and the TIMESTAMP literal produce the same result. nullstr returns NULL because the input is NULL.