查找序列中的缺失值

Question

表1如下：

Col1
1
2
3
4
6
7
8
9
10
13
14

如上所示，col1 具有值序列，但由于某种原因，用户没有插入 5、11 等。如何找出序列中的缺失值。这里的序列是 1 到 14，缺失值是 5,11。请帮帮我。

Answer 1

正如在其他答案中所说，最好的选择是使用真实的序列表进行连接。您可以使用递归 CTE 创建一个：

DECLARE @MaxNumber INT
SELECT @MaxNumber = MAX(Col1) FROM YourTable;

WITH CTE AS
(
    SELECT 1 Col1
    UNION ALL
    SELECT Col1+1
    FROM CTE 
    WHERE Col1+1 <= @MaxNumber
)
SELECT A.Col1
FROM CTE A
LEFT JOIN YourTable B
ON A.Col1 = B.Col1
WHERE B.Col1 IS NULL
OPTION(MAXRECURSION 0)

Answer 2

这适用于 0 - 2000 的大数字，您只需交叉加入原始结果集即可。

with temp as (
  select distinct number
from master..spt_Values
where number between 0 and 2000
)

select * from
temp t
left join your_table y on y.col1 = t.number
where y.col1 is null 

或者使用交叉连接

这对数十亿人的工作速度显然要慢

    WITH
      L0   AS(SELECT 1 AS c UNION ALL SELECT 1),
      L1   AS(SELECT 1 AS c FROM L0 AS A CROSS JOIN L0 AS B),
      L2   AS(SELECT 1 AS c FROM L1 AS A CROSS JOIN L1 AS B),
      L3   AS(SELECT 1 AS c FROM L2 AS A CROSS JOIN L2 AS B),
      L4   AS(SELECT 1 AS c FROM L3 AS A CROSS JOIN L3 AS B),
      L5   AS(SELECT 1 AS c FROM L4 AS A CROSS JOIN L4 AS B),
      Nums AS(SELECT ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) AS n FROM L5)

  select * from
    l5 t
    left join your_table y on y.col1 = t.n
    where y.col1 is null 

Answer 3

这似乎是重复

SQL query to find Missing sequence numbers

有一个可行的建议：

SELECT      l.id + 1 as start
FROM        Table1 as l
LEFT JOIN   Table1 as r on l.id + 1 = r.id
WHERE       r.id IS NULL

否则，您可以使用序列表在您的表上留下连接。从上面的问题，你可以看看http://www.projectdmx.com/tsql/tblnumbers.aspx，了解如何生成合适的序列表，join 会是这样的

SELECT      #sequence.value
FROM        #sequence
LEFT JOIN   Table1 ON #sequence.value = Table1.value
WHERE       Table1.value IS NULL

Answer 4

旁注对所有递归 CTE 建议。递归 CTE 增加时间与行数成线性关系。使用计数表或交叉连接要好得多...

这可行：

-- data table
CREATE TABLE #data (
    value INT
)

INSERT #data VALUES (1)
INSERT #data VALUES (2)
INSERT #data VALUES (3)
INSERT #data VALUES (4)
INSERT #data VALUES (6)
INSERT #data VALUES (7)
INSERT #data VALUES (8)
INSERT #data VALUES (9)
INSERT #data VALUES (10)
INSERT #data VALUES (13)
INSERT #data VALUES (14)

-- normally i have a tally table already for stuff like this but I'll
-- create one temporary here.
CREATE TABLE #tmp_tally (
    n INT
)

DECLARE @n INT
SET @n = 1
WHILE @n < 14
BEGIN
    INSERT #tmp_tally VALUES (@n)
    SET @n = @n + 1
END

SELECT
    T.n,
    CASE WHEN #data.value IS NULL THEN 'Missing' ELSE 'Not Missing' END
FROM
    #tmp_tally T
    LEFT JOIN #data ON
    T.n = #data.value
WHERE
    T.n <= (SELECT MAX(value) FROM #data) -- max of what you want to check against which is 14 in your example

DROP TABLE #data
DROP TABLE #tmp_tally

Answer 5

试试这个：

declare @min int
declare @max int

select @min = min(field_ID), @max = max(field_ID) from [Table]

create table #tmp (Field_No int)
while @min <= @max
begin
   if not exists (select * from [Table] where field_ID = @min)
      insert into #tmp (seq_field) values (@min)
   set @min = @min + 1
end
select * from #tmp
drop table #tmp

使用上述脚本，您将从#tmp 表的“ID”列中获取缺失值。

希望对你有帮助！！

Answer 6

我会在同一个表中做一个子查询，看看当前数字 1 是否存在另一个数字，如果不存在，你就知道跳过了一个数字。您也可以为此 +1。

选择 nt.numb, 案子 (select COUNT(*) from table where numb=nt.numb-1)=0 THEN 'skipped' ELSE 'not skipped' 从 数表nt