Order by last 3 months first, then alphabetically in MySQL?

Let us first create a table −

mysql> create table DemoTable1526
   -> (
   -> CustomerName varchar(20),
   -> PurchaseDate date
   -> );
Query OK, 0 rows affected (0.67 sec)

Insert some records in the table using insert command. Here, we have inserted 2019 dates −

mysql> insert into DemoTable1526 values('Adam','2019-06-01');
Query OK, 1 row affected (0.12 sec)
mysql> insert into DemoTable1526 values('Sam','2019-04-26');
Query OK, 1 row affected (0.13 sec)
mysql> insert into DemoTable1526 values('Chris','2019-05-24');
Query OK, 1 row affected (0.10 sec)
mysql> insert into DemoTable1526 values('David','2019-10-10');
Query OK, 1 row affected (0.23 sec)
mysql> insert into DemoTable1526 values('Bob','2019-12-31');
Query OK, 1 row affected (0.23 sec)

Display all records from the table using select statement −

mysql> select * from DemoTable1526;

This will produce the following output −

+--------------+--------------+
| CustomerName | PurchaseDate |
+--------------+--------------+
| Adam         |   2019-06-01 |
| Sam          |   2019-04-26 |
| Chris        |   2019-05-24 |
| David        |   2019-10-10 |
| Bob          |   2019-12-31 |
+--------------+--------------+
5 rows in set (0.00 sec)

The current date is as follows −

mysql> select curdate();
+------------+
| curdate()  |
+------------+
| 2019-10-08 |
+------------+
1 row in set (0.00 sec)

Here is the query to order by last 3 months first of 2019, then alphabetically −

mysql> select * from DemoTable1526
   -> order by PurchaseDate > curdate() - interval 3 month desc,CustomerName;

This will produce the following output −

+--------------+--------------+
| CustomerName | PurchaseDate |
+--------------+--------------+
| Bob          |   2019-12-31 |
| David        |   2019-10-10 |
| Adam         |   2019-06-01 |
| Chris        |   2019-05-24 |
| Sam          |   2019-04-26 |
+--------------+--------------+
5 rows in set (0.00 sec)