验证ID通过所有以前的阶段

Question

id  current stage  previous stages
1      06              05
1      06              03

2      04              03
2      04              02

假设有5个阶段的id（02,03,04等）。 id应该经历每个阶段。这里的示例Id = 1跳过04和02阶段，但id = 2跳过所有。所以它应该是当前阶段-1和-2等。

我必须识别跳过阶段的这类ID。我需要使用PostgreSQL查询。

Answer 1

假设当前/先前每个id都是唯一的：

select id
from tab
group by id
having min(previous_stage) <> 2           -- doesn't start with 2
    or max(current_stage) - 2 <> count(*) -- there's at least one missing stage

编辑：

如果distinct previous_stage中的id不唯一，则应用select id from tab group by id having min(previous_stage) <> 2 -- doesn't start with 2 or max(current_stage) - 2 <> count(distinct previous_stage) -- there's at least one missing stage 。

or

编辑：

我之前的查询逻辑错误，应该是and而不是select id from tab group by id having not -- these are the correct ids ( min(previous_stage) = 2 -- start with 2 and max(current_stage) - min(previous_stage) = count(distinct previous_stage) -- no missing steps and max(previous_stage) = max(current_stage) -1 -- no greater step ) 。 这应该涵盖您的要求：

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