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用SQL查询检查序列

sequence ms-access sql-server sql

THEn · 技术社区 · 15 年前

我有一张桌上订单,可以保存我们所有商店的所有订单。我编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

我可以查一下,所有的订单都有这个查询。web ordernumber是1到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少的订单?

4 回复 | 直到 14 年前

Andomar 15 年前

可以将表本身联接起来以检测没有前一行的行:

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1…n序列中的间隙,但不会检测重复项。

Alex Martelli 15 年前

我将生成一个“从1到n的所有整数”的辅助表(参见 http://www.sql-server-helper.com/functions/integer-table.aspx 对于某些使用SQL Server函数的方法,但由于这是您需要的东西,我会将它变成一个真正的表,而且对于任何SQL引擎,很容易做到这一点,只需一次),然后使用嵌套查询, SELECT value FROM integers WHERE value NOT IN (SELECT webordernumber FROM orders) &C。另请参见 http://www.sqlmag.com/Article/ArticleID/99797/sql_server_99797.html 对于类似于您的问题,“检测数字序列中的间隙”。

Tom Warfield 14 年前

如果您有rank()函数,但没有lag()函数(换句话说,SQL Server),则可以使用它(由 http://www.sqlmonster.com/Uwe/Forum.aspx/sql-server-programming/10594/Return-gaps-in-a-sequence ):

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“外部限制”:

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)

Tony Andrews 15 年前

如果您的数据库支持分析函数,然后您可以使用如下查询:

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

输出将显示间隙,例如

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

这意味着数字3到7(包括7)丢失了。