SQL：用連續值替換非連續值

Question

我有非連續但有序的數字標識符。我想獲得連續的值。

當前表：

original_value 

1 
1 
1 
3 
3 
29 
29 
29 
29 
1203 
1203 
5230304 
5230304 
5230304 
5230304 

所需的表：

original_value desired_value 

1    1 
1    1 
1    1 
3    2 
3    2 
29    3 
29    3 
29    3 
29    3 
1203    4 
1203    4 
5230304   5 
5230304   5 
5230304   5 
5230304   5 

Answer 1

另一種方法，無法加入：

select 

    original_value, 
    case when @original = original_value then 
    @group_number 
    else 
    @group_number := @group_number + 1 
    end, 
    (@original := original_value) as x 

from tbl,(select @original := null, @group_number := 0) z 
order by original_value 

現場測試：http://www.sqlfiddle.com/#!2/b82d6/6

如果你想刪除的結果計算，表導出查詢：

select w.original_value, w.group_number 
from 
(
    select 

    original_value, 
    case when @original = original_value then 
     @group_number 
    else 
     @group_number := @group_number + 1  
    end as group_number, 
    (@original := original_value) as x 

    from tbl,(select @original := null, @group_number := 0) z 
    order by original_value 
) w 

現場測試：http://www.sqlfiddle.com/#!2/b82d6/4

Answer 2

總結自己的價值觀，用行號以獲得您想要的值，然後再加入回原來的值：

SELECT t.original, sq.desired 
FROM Table t 
INNER JOIN(
    SELECT ssq.original, @rownum:=@rownum+1 ‘desired’ 
    FROM (
    SELECT t.original 
    FROM Table t 
    GROUP BY t.original 
    ORDER BY t.original 
) ssq, 
    (SELECT @rownum:=0) r 
) sq ON sq.original = t.original 

Answer 3

另一種方法，這一個模擬帶連接的DENSE_RANK：

SELECT t.original, d.derived 
     FROM t 
INNER JOIN ( SELECT t.original, COUNT(DISTINCT t1.original) AS "derived" 
        FROM t 
      INNER JOIN t t1 
         ON t.original >= t1.original 
       GROUP BY 1) d 
      ON t.original = d.original 
    ORDER BY t.original; 

Answer 4

如果我理解正確的話：

select 
    original_value, 
    dense_rank() over (order by original_value) as desired_value