如何找到重复和差距在这种情况下mysql

Question

你好，我有一个表，看起来像

-----------------------------------------------------------
|  id  |  group_id | source_id | target_id | sortsequence |
-----------------------------------------------------------
|  2   |    1      |    2      |   4       |     1        |   
-----------------------------------------------------------
|  4   |    1      |    20     |   2       |     1        |   
-----------------------------------------------------------
|  5   |    1      |    2      |   14      |     1        |   
-----------------------------------------------------------
|  7   |    1      |    2      |   7       |     3        |   
-----------------------------------------------------------
|  20  |    2      |    20     |   4       |     3        |   
-----------------------------------------------------------
|  21  |    2      |    20     |   4       |     1        |   
-----------------------------------------------------------

有两种情况需要处理。

1. Sortsequence列值在source_id和group_id中必须是唯一的。例如，如果所有具有group_id = 1 AND source_id = 2的记录都应该具有唯一的排序顺序。在上面的例子中，记录具有id= and 5 which are having group_id = 1 and source_id = 2 have same sortsequence which is 1。这是错误的记录。我需要找到这些记录。
2. 如果group_id and source_id相同。sortsequence columns value should be continous. There should be no gap。例如在上面的表records having id = 20, 21 having same group_id and source_id and sortsequence value is 3 and 1中。即使这是唯一的，但在排序序列值中存在差距。我也需要找到这些记录。

MY So Far Effort

我写了一个查询

SELECT source_id,`group_id`,GROUP_CONCAT(id) AS children 
FROM
    table 
GROUP BY source_id,
  sortsequence,
  `group_id` 
 HAVING COUNT(*) > 1 

该查询只针对场景1。如何处理场景2?是否有任何方法可以在相同的查询中做到这一点，或者我必须编写其他处理第二种情况。

By the way query will be dealing with million of records in table so performance must be very good.

Answer 1

从Tere J评论中得到答案。下面的查询涵盖了上述两个条件。

 SELECT 
     source_id, `group_id`, GROUP_CONCAT(id) AS faultyIDS    
 FROM
     table
 GROUP BY
     source_id,group_id 
 HAVING
     COUNT(DISTINCT sortsequence) <> COUNT(sortsequence) OR COUNT(sortsequence) <> MAX(sortsequence) OR MIN(sortsequence) <> 1

也许可以帮助别人。

Answer 2

试试这个查询，它将解决您在问题中提到的两种情况。

SELECT 
   a.* 
FROM 
   tbl a
INNER JOIN 
   (select 
       @rn:=IF(@prevG = group_id AND @prevS = source_id, @rn + 1, 1) As rId,
       @prevG:=group_id AS group_id, 
       @prevS:=source_id AS source_id, 
       id, 
       sortsequence
    FROM 
       tbl 
    join 
       (select @rn:=0, @prevS:=0, @prevG:=0)b
    order by group_id, source_id, id) b
ON a.id = b.id AND a.SORTSEQUENCE <> b.RID;

小提琴