今天看mysql的手册的时候发现这么一句:
 能够在带有“:=”赋值操作符的语句中设置变量。o                     mysql> SELECT @a:=SUM(total),@b=COUNT(*),@a/@b AS avg
o                         -> FROM test_table;
o                     mysql> SELECT @t1:=(@t2:=1)+@t3:=4,@t1,@t2,@t3;
但是我测试了一下:select value_type_sk,@a:=sum(detail_value) as a,@b:=count(*) as b,@a/@b as avg from tb_0_1_A_fact where value_time='2010-01-12'  group by value_type_sk;
结果却是
+---------------+------------+---+------------------------------------------+
| value_type_sk | a          | b | avg                                      |
+---------------+------------+---+------------------------------------------+
| 1             | 10863240   | 1 | 197871662.000000000000000000000000000000 |
| 2             | 9892944    | 1 | 197871662.000000000000000000000000000000 |
| 3             | 642106660  | 1 | 197871662.000000000000000000000000000000 |
| 4             | 587068769  | 1 | 197871662.000000000000000000000000000000 |
| 5             | 2147483647 | 1 | 197871662.000000000000000000000000000000 |
| 6             | 197871662  | 1 | 197871662.000000000000000000000000000000 |
+---------------+------------+---+------------------------------------------+
怎么都变成@a/@b最后一个结果的值了