从表中获取缺少的id

Question

我有tbl_profilecategory这样的表结构：

Id      col1
1       50
3       30
4       40
5       50
8       80
9       90

现在我想要表中缺少的ID，所以这里的结果应该是这样的：

Id= 2,6,7 

Answer 1

您可以使用

SELECT t1.id - 1 AS missing_id
FROM mytable t1
LEFT JOIN mytable t2 ON t2.id = t1.id - 1
WHERE t2.id IS NULL

Answer 2

此答案基于here

SELECT a.id+1 AS start, MIN(b.id) - 1 AS end
FROM testtable AS a, testtable AS b
WHERE a.id < b.id
GROUP BY a.id
HAVING start < MIN(b.id)