如何比較同一張表中的值

Question

Filename||status
---------------
A|10
A|22
B|10

我的預期輸出是

B|10

我不應獲得文件名同時為10和22的輸出狀態

Answer 1

讓我們嘗試重述您的問題-您正在尋找狀態為10但狀態不為22的文件。一旦這樣表達問題，我們就可以使用exists操作符輕松地將需求轉換為SQL ：

SELECT *
FROM   mytable a
WHERE  status = 10 AND
       NOT EXISTS (SELECT *
                   FROM   mytable b
                   WHERE  a.filename = b.filename AND
                          b.status = 22)

Answer 2

這是獲取結果的查詢：

WITH files AS(
    SELECT 'A' AS filename, 10 AS status FROM dual UNION ALL
    SELECT 'A' AS filename, 22 AS status FROM dual UNION ALL
    SELECT 'B' AS filename, 10 AS status FROM dual UNION ALL
    SELECT 'C' AS filename, 22 AS status FROM dual 
)
    SELECT filename, status
    FROM files
    WHERE filename NOT IN (
        SELECT f1.filename
        FROM files f1, files f2
        WHERE f1.filename = f2.filename
          AND f1.status = 22
          AND f2.status = 10
    );

我在表中添加了一條C記錄以檢查結果的正確性：

B   10                                    
C   22                                    

Answer 3

我不應獲得文件名同時為10和22的輸出狀態

換句話說，您可以具有狀態10且沒有狀態22行，也可以具有狀態22且沒有狀態10行。

這些查詢都不要求自聯接（它們都僅使用單個表掃描）：

查詢 ：

SELECT filename
FROM   table_name
GROUP BY filename
HAVING (   COUNT( CASE status WHEN 10 THEN 1 END ) > 0
       AND COUNT( CASE status WHEN 22 THEN 1 END ) = 0 )
OR     (   COUNT( CASE status WHEN 10 THEN 1 END ) = 0
       AND COUNT( CASE status WHEN 22 THEN 1 END ) > 0 );

輸出 ：

FILENAME
--------
B

查詢 ：

SELECT filename,
       status
FROM   (
  SELECT t.*,
         COUNT( CASE status WHEN 10 THEN 1 END )
           OVER ( PARTITION BY filename ) AS s10,
         COUNT( CASE status WHEN 22 THEN 1 END )
           OVER ( PARTITION BY filename ) AS s22
  FROM   table_name t
  WHERE  status IN ( 10, 22 )
)
WHERE  ( s10 > 0 AND s22 = 0 )
OR     ( s10 = 0 AND s22 > 0 );

輸出 ：

FILENAME STATUS
-------- ------
B            10

Answer 4

  select Filename, min(status)
    from [table_name]
  group by Filename
having count(*) = 1