用於查找值系列長度的SQL查詢

Question

我需要一個查詢來評估列中最長的不間斷系列後續「1」。對於表TEST(row_no number, fl_succ_exec number(1))中的以下數據，查詢結果應爲「6」。

行按row_no排序。

ROW_NO FL_SUCC_EXEC 
---------- ------------ 
     1   1 
     2   1 
     3   1 
     4   0 
     5   1 
     6   1 
     7   1 
     8   1 
     9   1 
     10   1 
     11   0        
     12   1 
     13   1 
     14   1 
     15   1 

我可以在PL/SQL做到這一點：

declare 
temp_cnt pls_integer default 0; 
total_cnt pls_integer default 0; 
begin 
for rec in (select row_no, fl_succ_exec from test order by row_no) 
loop 
    if temp_cnt > total_cnt 
    then 
    total_cnt:=temp_cnt; 
    end if; 

    if rec.fl_succ_exec!=0 
    then 
    temp_cnt:=temp_cnt+rec.fl_succ_exec; 
    else 
    temp_cnt:=0; 
    end if; 

end loop; 
dbms_output.put_line(total_cnt); 
end; 

但我仍然希望SQL解決方案。有沒有？

Answer 1

嘗試：

SELECT max(count(*)) As longest_uninterrupted_series 
FROM (
    select fl_succ_exec, 
      sum(case when fl_succ_exec = 1 then 0 else 1 end) 
       over (order by row_no) xx 
    from test 
) 
WHERE fl_succ_exec = 1 
GROUP BY xx; 

Answer 2

甲骨文設置：

CREATE TABLE test (row_no, fl_succ_exec) AS 
    SELECT 1, 1 FROM DUAL UNION ALL 
    SELECT 2, 1 FROM DUAL UNION ALL 
    SELECT 3, 1 FROM DUAL UNION ALL 
    SELECT 4, 0 FROM DUAL UNION ALL 
    SELECT 5, 1 FROM DUAL UNION ALL 
    SELECT 6, 1 FROM DUAL UNION ALL 
    SELECT 7, 1 FROM DUAL UNION ALL 
    SELECT 8, 1 FROM DUAL UNION ALL 
    SELECT 9, 1 FROM DUAL UNION ALL 
    SELECT 10, 1 FROM DUAL UNION ALL 
    SELECT 11, 0 FROM DUAL UNION ALL 
    SELECT 12, 1 FROM DUAL UNION ALL 
    SELECT 13, 1 FROM DUAL UNION ALL 
    SELECT 14, 1 FROM DUAL UNION ALL 
    SELECT 15, 1 FROM DUAL; 

查詢：

SELECT MAX(num_1s) AS num_1s 
FROM (
    SELECT COALESCE(
      row_no - LAST_VALUE(CASE fl_succ_exec WHEN 0 THEN row_no END) 
         IGNORE NULLS OVER (ORDER BY row_no), 
      ROWNUM 
     ) AS num_1s 
    FROM test 
); 

輸出：

NUM_1S 
------ 
    6