问题
In my query, I am doing multiple types of ranking and for one of ranking types, I want to rank the row only if certain column is not null. Else I don't want ranking to happen.
For example here's a sample table:
+------+------------+------------+--------+--------+
| col1 | col2 | col3 | rank 1 | rank 2 |
+------+------------+------------+--------+--------+
| a | 2018-01-20 | 2018-03-04 | 2 | 2 |
| a | 2018-01-24 | 2018-04-04 | 1 | 1 |
| b | 2018-01-02 | 2018-05-03 | 1 | 1 |
| c | 2017-01-02 | 2017-05-08 | 3 | 2 |
| d | 2016-05-24 | null | 1 | null |
| c | 2018-02-05 | 2018-05-03 | 2 | 1 |
| c | 2018-07-28 | null | 1 | null |
+------+------------+------------+--------+--------+
rank1 is calculated alright based on partition by col1 order by col2 desc
rank 2 should be calculated the same way, but only when when col3 is null, else it should be null.
How can I achieve both ranks in a single query? I tried to use case statement for rank2, but it skips the ranking when col3 is null,
回答1:
If I understand corrcly, you can try to use CASE WHEN
with sum
window function
CASE WHEN
check col3
isn't null
do accumulate else display NULL
CREATE TABLE T(
col1 VARCHAR(5),
col2 DATE,
col3 DATE
);
INSERT INTO T VALUES ( 'a' , to_date('2018-01-20','YYYY-MM-DD') , to_date('2018-03-04','YYYY-MM-DD'));
INSERT INTO T VALUES ( 'a' , to_date('2018-01-24','YYYY-MM-DD') , to_date('2018-04-04','YYYY-MM-DD'));
INSERT INTO T VALUES ( 'b' , to_date('2018-01-02','YYYY-MM-DD') , to_date('2018-05-03','YYYY-MM-DD'));
INSERT INTO T VALUES ( 'c' , to_date('2017-01-02','YYYY-MM-DD') , to_date('2017-05-08','YYYY-MM-DD'));
INSERT INTO T VALUES ( 'd' , TO_DATE('2016-05-24','YYYY-MM-DD') , null);
INSERT INTO T VALUES ( 'c' , TO_DATE('2018-02-05','YYYY-MM-DD') , to_date('2018-05-03','YYYY-MM-DD'));
INSERT INTO T VALUES ( 'c' , TO_DATE('2018-07-28','YYYY-MM-DD') , null);
Query 1:
select t1.*,
rank() OVER(partition by col1 order by col2 desc) rank1,
(CASE WHEN COL3 IS NOT NULL THEN
SUM(CASE WHEN COL3 IS NOT NULL THEN 1 ELSE 0 END) OVER(partition by col1 order by col2 desc)
ELSE
NULL
END) rank2
FROM T t1
Results:
| COL1 | COL2 | COL3 | RANK1 | RANK2 |
|------|----------------------|----------------------|-------|--------|
| a | 2018-01-24T00:00:00Z | 2018-04-04T00:00:00Z | 1 | 1 |
| a | 2018-01-20T00:00:00Z | 2018-03-04T00:00:00Z | 2 | 2 |
| b | 2018-01-02T00:00:00Z | 2018-05-03T00:00:00Z | 1 | 1 |
| c | 2018-07-28T00:00:00Z | (null) | 1 | (null) |
| c | 2018-02-05T00:00:00Z | 2018-05-03T00:00:00Z | 2 | 1 |
| c | 2017-01-02T00:00:00Z | 2017-05-08T00:00:00Z | 3 | 2 |
| d | 2016-05-24T00:00:00Z | (null) | 1 | (null) |
回答2:
I think you might want:
select count(col3) over (partition by col1 order by col2 desc)
Note that this is equivalent to row_number()
rather than rank()
. For your data these are equivalent.
来源:https://stackoverflow.com/questions/51895196/oracle-sql-conditional-ranking