我怎样才能像 mysql 这样在 oracle 中写排名 sql

Question

我的 sql 段在 mysql:

SELECT t.*,@r1:=@r1+1 r1,@r:=IF(@v=score OR(@v IS NULL AND score IS NULL),@r,@r1) rank,@v:=score v1 
FROM(SELECT @r :=0) a,(SELECT @r1 :=0) b,(SELECT @v:=NULL) v,(SELECT id,score FROM exam_inst 
WHERE eid = '1161918326813872128' AND type = 2 GROUP BY dealer 
ORDER BY i_level DESC,create_date DESC) t ORDER BY score DESC

我想在 Oracle 中编写相同的查询 sql，我该怎么做？

table:

A     B
c1    a
c1    b
c1    a
c2    a
c2    a
c2    b

查询结果：

A     B    R
c1    a    1
c1    b    2
c1    a    3
c2    a    1
c2    a    1
c2    b    3

Answer 1

使用RANK解析函数：

SELECT t.*,
       RANK() OVER ( PARTITION BY a ORDER BY b ) AS r
FROM   table_name t;

或您的示例数据：

CREATE TABLE table_name ( a, b ) AS
SELECT 'c1', 'a' FROM DUAL UNION ALL
SELECT 'c1', 'b' FROM DUAL UNION ALL
SELECT 'c1', 'a' FROM DUAL UNION ALL
SELECT 'c2', 'a' FROM DUAL UNION ALL
SELECT 'c2', 'a' FROM DUAL UNION ALL
SELECT 'c2', 'b' FROM DUAL;

这输出：

A  | B  |  R
:- | :- | -:
c1 | a  |  1
c1 | a  |  1
c1 | b  |  3
c2 | a  |  1
c2 | a  |  1
c2 | b  |  3

db<>fiddle here

更新

I just want to compare adjacent rows，i do not care about how many 'a'

SQL 中的行未排序；所以你需要另一列来存储行的顺序：

CREATE TABLE table_name ( a, b, c ) AS
SELECT 'c1', 'a', 1 FROM DUAL UNION ALL
SELECT 'c1', 'b', 2 FROM DUAL UNION ALL
SELECT 'c1', 'a', 3 FROM DUAL UNION ALL
SELECT 'c2', 'a', 1 FROM DUAL UNION ALL
SELECT 'c2', 'a', 2 FROM DUAL UNION ALL
SELECT 'c2', 'b', 3 FROM DUAL;

这将找到行的密集排名：

SELECT a,
       b,
       c,
       SUM( has_changed ) OVER ( PARTITION BY a ORDER BY c ) AS r
FROM   (
  SELECT t.*,
         CASE
         WHEN b = LAG( b ) OVER ( PARTITION BY a ORDER BY c )
         THEN 0
         ELSE 1
         END AS has_changed
  FROM   table_name t
)
ORDER BY a, c;

输出：

A  | B  |  C |  R
:- | :- | -: | -:
c1 | a  |  1 |  1
c1 | b  |  2 |  2
c1 | a  |  3 |  3
c2 | a  |  1 |  1
c2 | a  |  2 |  1
c2 | b  |  3 |  2

如果您想要（稀疏）排名，那么您可以获取之前的输出并对其应用 RANK 分析函数：

SELECT a,
       b,
       c,
       RANK() OVER ( PARTITION BY a ORDER BY r ) AS r
FROM   (
  SELECT a,
         b,
         c,
         SUM( has_changed ) OVER ( PARTITION BY a ORDER BY c ) AS r
  FROM   (
    SELECT t.*,
           CASE
           WHEN b = LAG( b ) OVER ( PARTITION BY a ORDER BY c )
           THEN 0
           ELSE 1
           END AS has_changed
    FROM   table_name t
  )
)
ORDER BY a, c;

输出：

A  | B  |  C |  R
:- | :- | -: | -:
c1 | a  |  1 |  1
c1 | b  |  2 |  2
c1 | a  |  3 |  3
c2 | a  |  1 |  1
c2 | a  |  2 |  1
c2 | b  |  3 |  3

您还可以使用 MATCH_RECOGNIZE 来比较连续的行：

SELECT a,
       b,
       c,
       dense_rank,
       RANK() OVER( PARTITION BY a ORDER BY dense_rank ) AS sparse_rank
FROM   table_name
MATCH_RECOGNIZE (
   PARTITION BY a
   ORDER BY     c
   MEASURES     MATCH_NUMBER() AS dense_rank
   ALL ROWS PER MATCH
   PATTERN      (FIRST_ROW EQUAL_ROWS*)
   DEFINE       EQUAL_ROWS AS EQUAL_ROWS.b = PREV(EQUAL_ROWS.b)
)

输出：

A  | B  |  C | DENSE_RANK | SPARSE_RANK
:- | :- | -: | ---------: | ----------:
c1 | a  |  1 |          1 |           1
c1 | b  |  2 |          2 |           2
c1 | a  |  3 |          3 |           3
c2 | a  |  1 |          1 |           1
c2 | a  |  2 |          1 |           1
c2 | b  |  3 |          2 |           3

db<>fiddle here

我怎样才能像 mysql 这样在 oracle 中写排名 sql

how can i write rank sql in oracle like mysql

mysql

oracle

rank

更新