T-SQL: get only rows which are after a row that meets some condition

Question

I have a table of article's logs. I need to get all the articles which have only one log, or in case there are amount of logs more than 1: if an article has any log in status = 103, it's need to fetch only rows after this log, in other case all the logs. So from the following dataset I want to get only rows with Id 1383 and 284653.

Id	Article	Version	StatusId	AddedDate
1383	1481703	0	42	2011-11-25 09:23:42.000
284645	435545	1	41	2021-11-02 18:29:42.000
284650	435545	2	41	2021-11-02 18:34:58.000
284651	435545	2	103	2021-11-02 18:34:58.000
284653	435545	3	41	2021-11-02 18:38:33.000

Any ideas how to handle it properly ? Thanks in advance

Answer 1

You can use window functions here. A combination of a running COUNT and a windowed COUNT will do the trick

The benefit of using window functions rather than self-joins is that you only scan the base table once.

SELECT
  Id,
  Article,
  Version,
  StatusId,
  AddedDate
FROM (
    SELECT *,
      HasPrev103 = COUNT(CASE WHEN StatusId = 103 THEN 1 END) OVER
              (PARTITION BY Article ORDER BY AddedDate ROWS BETWEEN UNBOUNDED PRECEDING AND 1 PRECEDING),
      Has103 = COUNT(CASE WHEN StatusId = 103 THEN 1 END) OVER (PARTITION BY Article),
      Count = COUNT(*) OVER (PARTITION BY Article)
    FROM YourTable t
) t
WHERE (Has103 > 0 AND HasPrev103 > 0) OR Count = 1;

db<>fiddle

Answer 2

CREATE TABLE #Article (
    Id int NOT NULL PRIMARY KEY,
    Article int NOT NULL,
    Version int NOT NULL,
    StatusId int NOT NULL,
    DateAdded datetime NOT NULL
)

INSERT INTO #Article (Id, Article, Version, StatusId, DateAdded)
VALUES
    (1383,  1481703,    0,  42,     '2011-11-25 09:23:42.000'),
    (284645, 435545,    1,  41 ,    '2021-11-02 18:29:42.000'),
    (284650, 435545,    2,  41 ,    '2021-11-02 18:34:58.000'),
    (284651, 435545,    2,  103,    '2021-11-02 18:34:58.000'),
    (284653, 435545,    3,  41 ,    '2021-11-02 18:38:33.000')

SELECT *
FROM #Article a
    LEFT JOIN (
        -- Get articles that appear only once.
        SELECT Article
        FROM #Article
        GROUP BY Article
        HAVING COUNT(*) = 1
    ) AS o
        ON a.Article = o.Article
    LEFT JOIN (
        -- Get the 103s and their corresponding date.
        SELECT Article, DateAdded
        FROM #Article
        WHERE StatusId = 103
    ) AS s
        ON a.Article = s.Article AND s.DateAdded < a.DateAdded
WHERE o.Article IS NOT NULL OR (s.Article IS NOT NULL AND a.DateAdded > s.DateAdded)

DROP TABLE #Article