Fetch records from interval of past 3 days from current date in MySQL and add the corresponding records

Let us first create a table −

mysql> create table DemoTable
(
   ProductAmount int,
   PurchaseDate datetime
);
Query OK, 0 rows affected (0.94 sec)

Note − Let’s say the current date is 2010-09-15.

Insert some records in the table using insert command −

mysql> insert into DemoTable values(567,'2019-09-10');
Query OK, 1 row affected (0.17 sec)
mysql> insert into DemoTable values(1347,'2019-09-14');
Query OK, 1 row affected (0.16 sec)
mysql> insert into DemoTable values(2033,'2019-09-13');
Query OK, 1 row affected (0.23 sec)
mysql> insert into DemoTable values(1256,'2019-09-11');
Query OK, 1 row affected (0.12 sec)
mysql> insert into DemoTable values(1000,'2019-09-16');
Query OK, 1 row affected (0.14 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable;

This will produce the following output −

+---------------+---------------------+
| ProductAmount | PurchaseDate        |
+---------------+---------------------+
|           567 | 2019-09-10 00 :00 :00 |
|          1347 | 2019-09-14 00:00 :00 |
|          2033 | 2019-09-13 00:00 :00 |
|          1256 | 2019-09-11 00:00 :00 |
|          1000 | 2019-09-16 00:00 :00 |
+---------------+---------------------+
5 rows in set (0.00 sec)

Following is the query to use now() function in MySQL query −

mysql> select sum(ProductAmount) from DemoTable
   where PurchaseDate > NOW()- interval 3 day;

This will produce the following output −

+--------------------+
| sum(ProductAmount) |
+--------------------+
|             4380   |
+--------------------+
1 row in set (0.00 sec)