Question 26: Given the situation below, what is the result of the following query?

create table grptst
  (s_dt date, s_shop int, sales decimal(10,2), key ix1(s_shop,s_dt));
insert into grptst
  values ('2010-01-01',1,1000.00),('2010-01-01',2,1000.00),
         ('2010-01-01',1,1000.00),('2010-01-01',2,null),
         ('2010-01-01',null,5000.50),('2010-01-01',null,5000.50);
 
select s_shop,s_dt,sum(sales)
  from grptst group by s_shop,s_dt order by 1,2;
 
a)
+--------+------------+------------+
| s_shop | s_dt       | sum(sales) |
+--------+------------+------------+
|      1 | 2010-01-01 |    2000.00 |
|      2 | 2010-01-01 |    1000.00 |
+--------+------------+------------+
2 rows in set (0.01 sec)
 
b)
+--------+------------+------------+
| s_shop | s_dt       | sum(sales) |
+--------+------------+------------+
|   NULL | 2010-01-01 |   10001.00 |
|      1 | 2010-01-01 |    2000.00 |
|      2 | 2010-01-01 |    1000.00 |
+--------+------------+------------+
3 rows in set (0.02 sec)
 
c)
+--------+------------+------------+
| s_shop | s_dt       | sum(sales) |
+--------+------------+------------+
|   NULL | 2010-01-01 |   10001.00 |
|      1 | 2010-01-01 |    2000.00 |
|      2 | 2010-01-01 |       NULL |
+--------+------------+------------+
3 rows in set (0.02 sec)
 
d)
+--------+------------+------------+
| s_shop | s_dt       | sum(sales) |
+--------+------------+------------+
|   NULL |       NULL |       NULL |
|      1 | 2010-01-01 |    2000.00 |
|   NULL |       NULL |       NULL |
+--------+------------+------------+
3 rows in set (0.02 sec)

 
[ Querying for Data (15%) - Aggregating Results, Grouping Results ]