从 table 中筛选出序列中存在间隙的那些数据

Question

如果提到的任何目标之间的以下数据为空，我想将 doprocess 标志设置为 0

示例：

create table TestSAMP (
  id int identity(1,1),
  modelid navrchar(max),
  target1 nvarchar(max),
  target2 nvarchar(max),
  target3 nvarchar(max),
  target4 nvarchar(max),
  doprcoess  int default(1)
)

--VALID SET DOPROCESS FLAG TO 1
INSERT INTO TestSAMP(modelid,target1,target2,target3,target4) 
VALUES('1','T1','T2','T3','T4')

--NOTVALID SET DOPROCESS FLAG TO 0 DUE TO THE DATA IS MISSING IN SEQUENCE 
INSERT INTO TestSAMP(modelid,target1,target2,target3,target4)
VALUES('2','TR','','T3','T4')

--VALID SET DOPROCESS FLAG TO 1 As if data is present
-- it should be present insequence in below t1 t2 as they arfe in sequence
INSERT INTO TestSAMP(modelid,target1,target2,target3,target4)
VALUES('3','T1','T2','','')

--NOTVALID SET DOPROCESS FLAG TO 0 DUE TO THE DATA IS MISSING IN SEQUENCE 
--where T4 data is provided and not in T3
INSERT INTO TestSAMP(modelid,target1,target2,target3,target4) 
VALUES('4','T1','T2','','T4')

I have got lot of solution where people try out to find the sequential number but here the case is nvarchar

Answer 1

最简单的方法应该是使用布尔表达式检查前任是否为空而后继者是否为空。

UPDATE testsamp
       SET doprocess = 0
       WHERE target2 <> ''
             AND target1 = ''
              OR target3 <> ''
                 AND target2 = ''
               OR target4 <> ''
                   AND target3 = '';

您可能想要扩展它，例如，如果它也无效，当所有目标都为空时。不知道你要不要。

Answer 2

您可以将间隙和岛视为字符串，即 'IGGI'，压缩它，然后搜索 'IGI' 模式：

SELECT *, CASE WHEN squashed LIKE '%IGI%' THEN 0 ELSE 1 END AS new_doprocess
FROM TestSAMP t
CROSS APPLY(SELECT STRING_AGG(CASE WHEN t = '' THEN 'G' ELSE 'I'END, '') r
             FROM (VALUES (1,id, target1), (2,id, target2),
                          (3,id, target3), (4,id, target4)) sub(rn, id, t)) s
CROSS APPLY (SELECT replace(replace(replace(replace(replace(replace(s.r,'G','<>')
   ,'><',''),'<>','G'),'I','<>'),'><',''),'<>','I')) AS sub(squashed)
ORDER BY t.id;

db<>fiddle demo

示例：

  id  | target1  | target2  | target3  | target4  |  r    | squashed  | doprocess 
 -----|----------|----------|----------|----------|-------|-----------|----------- 
   1  | T1       | T2       | T3       | T4       | IIII  | I         |         1 
   2  | T1       |          | T3       | T4       | IGII  | IGI       |         0 
   3  | T1       | T2       |          |          | IIGG  | IG        |         1 
   4  | T1       | T2       |          | T4       | IIGI  | IGI       |         0 
   5  |          |          |          | T4       | GGGI  | GI        |         1 
   6  |          |          |          |          | GGGG  | G         |         1

从 table 中筛选出序列中存在间隙的那些数据

Filter those data from table where there is a gap in sequence

sql

tsql

sql-server

gaps-and-islands