how to add date is sql code example

Example 1: sql add days to date

//Returns Date time
//Takes where to add (as in year, month, day, etc) to
//Takes how much to add
//Takes a datetime in some different formats
DATEADD(day, 1, '2017/08/25')

Example 2: how to add amount between date in sql

mysql> select sum(Value) from DemoTable1444 where PurchaseDate between '2019-10-02' and '2019-12-31';