DATE_SUB - Realtime Compute for Apache Flink - Alibaba Cloud Documentation Center

The topic describes how to use the DATE_SUB function. This function subtracts specific days from a date and then returns the obtained date.

Limits

This function is supported only in Realtime Compute for Apache Flink that uses Ververica Runtime (VVR) 3.0.0 or later.

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


Parameter	Data type
startdate	VARCHAR Note A date of the VARCHAR type is in the yyyy-MM-dd or yyyy-MM-dd HH:mm:ss format.
time	TIMESTAMP
days	INT

Note If an input parameter is NULL or a parsing error occurs, NULL is returned.

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;

Test result


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