*: fix query statement detail error cause by round

[crazycs520]

Signed-off-by: crazycs520 crazycs520@gmail.com

When query statement detail, dashboard uses to use ROUND function to query, but it may cause the flowing error:

This is caused by the ROUND function result is float64, not int, here is an example.

test> create table t (a int, b double);
Query OK, 0 rows affected
Time: 0.044s
test> insert into t values (62695, 2240325.4838709678),(6, 0.0);
Query OK, 2 rows affected
Time: 0.042s
test> select round(sum(a*b)/sum(a)) as avg from t;
+-----------+
| avg       |
+-----------+
| 2240111.0 |
+-----------+

This PR use CAST( ... AS SIGNED) function instead of ROUND when query statement detail.

[crazycs520]

@breeswish @baurine PTAL