#
# Try DENSE_RANK() function
#
create table t1 (
pk int primary key,
a int,
b int
);
insert into t1 values
( 1 , 0, 10),
( 2 , 0, 10),
( 3 , 1, 10),
( 4 , 1, 10),
( 8 , 2, 10),
( 5 , 2, 20),
( 6 , 2, 20),
( 7 , 2, 20),
( 9 , 4, 20),
(10 , 4, 20);
select pk, a, b, rank() over (order by a) as rank,
dense_rank() over (order by a) as dense_rank
from t1;
pk	a	b	rank	dense_rank
1	0	10	1	1
2	0	10	1	1
3	1	10	3	2
4	1	10	3	2
8	2	10	5	3
5	2	20	5	3
6	2	20	5	3
7	2	20	5	3
9	4	20	9	4
10	4	20	9	4
select pk, a, b, rank() over (partition by b order by a) as rank,
dense_rank() over (partition by b order by a) as dense_rank
from t1;
pk	a	b	rank	dense_rank
1	0	10	1	1
2	0	10	1	1
3	1	10	3	2
4	1	10	3	2
8	2	10	5	3
5	2	20	1	1
6	2	20	1	1
7	2	20	1	1
9	4	20	4	2
10	4	20	4	2
drop table t1;
#
# Test with null values in the table.
#
create table t2 (s1 int, s2 char(5));
insert into t2 values (1,'a');
insert into t2 values (null,null);
insert into t2 values (1,null);
insert into t2 values (null,'a');
insert into t2 values (null,'c');
insert into t2 values (2,'b');
insert into t2 values (-1,'');
select *, rank() over (order by s1) as rank,
dense_rank() over (order by s1) as dense_rank
from t2;
s1	s2	rank	dense_rank
1	a	5	3
NULL	NULL	1	1
1	NULL	5	3
NULL	a	1	1
NULL	c	1	1
2	b	7	4
-1		4	2
select *, rank() over (partition by s2 order by s1) as rank,
dense_rank() over (partition by s2 order by s1) as dense_rank
from t2;
s1	s2	rank	dense_rank
1	a	2	2
NULL	NULL	1	1
1	NULL	2	2
NULL	a	1	1
NULL	c	1	1
2	b	1	1
-1		1	1
select *, rank() over (order by s2) as rank,
dense_rank() over (order by s2) as dense_rank
from t2;
s1	s2	rank	dense_rank
1	a	4	3
NULL	NULL	1	1
1	NULL	1	1
NULL	a	4	3
NULL	c	7	5
2	b	6	4
-1		3	2
select *, rank() over (partition by s1 order by s2) as rank,
dense_rank() over (partition by s1 order by s2) as dense_rank
from t2;
s1	s2	rank	dense_rank
1	a	2	2
NULL	NULL	1	1
1	NULL	1	1
NULL	a	2	2
NULL	c	3	3
2	b	1	1
-1		1	1
drop table t2;