mysql去除重复record

Question

现在有这样一个需求，表里面有5个字段，前四列相同，而第五列不同的记录可能有多条，这种情况算是重复的，现只需要取前四列不同的记录，比如：现在有前四列都相同第五列不同的5条记录，需要的结果是：一条（前四列的四个字段），请问我该怎么写sql啊？谢谢！
比如数据如下：+------------+---------+---------+---------+---------+
| date       | imp_num | clk_num | rev_num | rule_id |
+------------+---------+---------+---------+---------+
| 2012-11-06 |     101 |      58 | 28.0121 |      23 |
| 2012-11-06 |     101 |      58 | 28.0121 |      47 |
| 2012-11-06 |      11 |       1 | 24.7487 |      23 |
| 2012-11-06 |      11 |       1 | 24.7487 |      45 |
| 2012-11-06 |     252 |       2 | 20.4423 |      26 |
| 2012-11-06 |     252 |       2 | 20.4423 |      47 |
| 2012-11-06 |     375 |      23 | 55.7518 |      23 |
| 2012-11-06 |     446 |     203 | 50.0405 |      40 |
| 2012-11-06 |     417 |       1 | 24.8505 |      47 |
| 2012-11-06 |     444 |     118 | 53.5241 |      23 |
+------------+---------+---------+---------+---------+
10 rows in set (0.00 sec)我想要的结果是：+------------+---------+---------+---------+---------+
| date       | imp_num | clk_num | rev_num | rule_id |
+------------+---------+---------+---------+---------+
| 2012-11-06 |     101 |      58 | 28.0121 |      23 |
| 2012-11-06 |      11 |       1 | 24.7487 |      23 |
| 2012-11-06 |     252 |       2 | 20.4423 |      26 |
| 2012-11-06 |     375 |      23 | 55.7518 |      23 |
| 2012-11-06 |     446 |     203 | 50.0405 |      40 |
| 2012-11-06 |     417 |       1 | 24.8505 |      47 |
| 2012-11-06 |     444 |     118 | 53.5241 |      23 |
+------------+---------+---------+---------+---------+

Answer 1

select * from table1
group by date , imp_num,clk_num,rev_num 

Answer 2

谢谢狼王，我原来以为group by后面只能跟一个字段的原来可以是组合，啊菜鸟！