使用SQL查询检查序列

Question

我有一个表格命令可以保持我们所有商店的所有订单。 我写了一个查询来检查每个商店的顺序订单。 看起来像那样。

select WebStoreID, min(webordernumber), max(webordernumber), count(webordernumber) 
from orders 
where ordertype = 'WEB' 
group by WebStoreID 

我可以检查所有订单是否与此查询一起存在。网上订单号是1 ... n之间的数字。

如何在不加入临时/不同表的情况下编写查询来查找缺失的订单？

Answer 1

您可以加入表上本身能检测到在没有上一行行：

select cur.* 
from orders cur 
left join orders prev 
    on cur.webordernumber = prev.webordernumber + 1 
    and cur.webstoreid = prev.webstoreid 
where cur.webordernumber <> 1 
and prev.webordernumer is null 

这将检测在1个... N序列的空白，但它不会检测重复。

Answer 2

我会制作一个“从1到n的所有整数”的辅助表（请参阅http://www.sql-server-helper.com/functions/integer-table.aspx了解使用SQL Server功能的一些方法，但由于这是您需要反复处理的内容，所以我会将其纳入一个真正的表，无论如何，任何SQL引擎都很容易实现，只需要一次），然后使用嵌套查询SELECT value FROM integers WHERE value NOT IN (SELECT webordernumber FROM orders) & c。另请参阅http://www.sqlmag.com/Article/ArticleID/99797/sql_server_99797.html，查看与您的问题类似的问题，“检测数字序列中的空白”。

Answer 3

如果你的数据库支持分析功能，那么你可以使用查询类似：

select prev+1, curr-1 from 
(select webordernumber curr, 
     coalesce (lag(webordernumber) over (order by webordernumber), 0) prev 
    from orders 
) 
where prev != curr-1; 

输出将显示空白例如

prev+1 curr-1 
------ ------ 
    3  7 

意味着缺少数字3到7。

Answer 4

如果你有秩（）函数，而不是滞后（）函数（换句话说，SQL Server）的，你可以使用这个（由http://www.sqlmonster.com/Uwe/Forum.aspx/sql-server-programming/10594/Return-gaps-in-a-sequence建议）：

create table test_gaps_in_sequence (x int) 
insert into test_gaps_in_sequence values (1) 
insert into test_gaps_in_sequence values (2) 
insert into test_gaps_in_sequence values (4) 
insert into test_gaps_in_sequence values (5) 
insert into test_gaps_in_sequence values (8) 
insert into test_gaps_in_sequence values (9) 
insert into test_gaps_in_sequence values (12) 
insert into test_gaps_in_sequence values (13) 
insert into test_gaps_in_sequence values (14) 
insert into test_gaps_in_sequence values (29) 

...

select lower_bound 
     , upper_bound 
     from (select upper_bound 
       , rank() over (order by upper_bound) - 1 as upper_rank 
       from (SELECT x+n as upper_bound 
         from test_gaps_in_sequence 
         , (SELECT 0 n 
          UNION 
          SELECT -1 
          ) T 
        GROUP BY x+n 
        HAVING MAX(n) = -1 
        ) upper_1 
      ) upper_2 
     , (select lower_bound 
       , rank() over (order by lower_bound) as lower_rank 
       from (SELECT x+n as lower_bound 
         from test_gaps_in_sequence 
         , (SELECT 0 n 
          UNION 
          SELECT 1 
          ) T 
        GROUP BY x+n 
        HAVING MIN(n) = 1 
        ) lower_1 
      ) lower_2 
     where upper_2.upper_rank = lower_2.lower_rank 
     order by lower_bound 

...或者，包括“外部界限”：

select lower_bound 
    , upper_bound 
    from (select upper_bound 
      , rank() over (order by upper_bound) - 1 as upper_rank 
      from (SELECT x+n as upper_bound 
        from test_gaps_in_sequence 
        , (SELECT 0 n 
         UNION 
         SELECT -1 
         ) T 
       GROUP BY x+n 
       HAVING MAX(n) = -1 
       ) upper_1 
     ) upper_2 
    full join (select lower_bound 
      , rank() over (order by lower_bound) as lower_rank 
      from (SELECT x+n as lower_bound 
        from test_gaps_in_sequence 
        , (SELECT 0 n 
         UNION 
         SELECT 1 
         ) T 
       GROUP BY x+n 
       HAVING MIN(n) = 1 
       ) lower_1 
     ) lower_2 
    on upper_2.upper_rank = lower_2.lower_rank 
    order by coalesce (lower_bound, upper_bound)