sql - 使用 sqlite 计算列状态转换

Question

我需要计算每个代理的布尔列更改为 NO 的次数。或者每个代理从 YES 转换为 NO 的次数（以更容易的为准）示例：

预期结果：agent_A、2 agent_B、0

Answer 1

基本上，您需要先前的值和累积总和。SQLite 不支持窗口函数，所以这些很棘手。

select t.*,
       (select t2.status
        from t t2
        where t2.agent = t.agent and t2.datescan < t.datescan
        order by t2.datescan desc
        limit 1
       ) as prev_status
from t;

接下来，您需要识别更改及其累积总和：

with tt as (
      select t.*,
             (select t2.status
              from t t2
              where t2.agent = t.agent and t2.datescan < t.datescan
              order by t2.datescan desc
              limit 1
             ) as prev_status
      from t
     )
select tt.*,
       (select count(*)
        from tt tt2
        where tt2.agent = tt.agent and tt2.datescan < t.datescan and
              tt2.status = 'NO' and tt2.prev_status = 'YES'
      ) as counter
from tt;