按日期分组大于SQL Server

Question

我正在使用Micrososft SqlServer 2012，我有这张表：

表格

+-----------+--------+------------+
| Id_Client | Amount | Date       |
+-----------+--------+------------+
| 1         | 100    | 24/08/2015 |
| 2         | 100    | 24/07/2015 |
| 3         | 100    | 24/06/2015 |
| 3         | 100    | 24/05/2015 |
+-----------+--------+------------+

我需要进行这样的查询：

查询

SELECT ID_CLIENT, 
CASE WHEN DATE <= '01/07/2015' THEN 'OLD' ELSE 'NEW' END,
SUM(AMOUNT) FROM TABLE 
GROUP BY ID_CLIENT

如何按条件分组，而不是每个日期？ 我希望有类似的东西：

预期结果

+---+-----+-----+
| 1 | NEW | 100 |
| 2 | NEW | 100 |
| 3 | OLD | 200 |
+---+-----+-----+