# Report Contiguous Dates Problem

## Description

LeetCode Problem 1225.

Table: Failed

``````1
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+--------------+---------+
| Column Name  | Type    |
+--------------+---------+
| fail_date    | date    |
+--------------+---------+
Primary key for this table is fail_date.
Failed table contains the days of failed tasks.
``````

Table: Succeeded

``````1
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+--------------+---------+
| Column Name  | Type    |
+--------------+---------+
| success_date | date    |
+--------------+---------+
Primary key for this table is success_date.
Succeeded table contains the days of succeeded tasks.
``````

Write an SQL query to generate a report of period_state for each continuous interval of days in the period from 2019-01-01 to 2019-12-31.

period_state is ‘failed’ if tasks in this interval failed or ‘succeeded’ if tasks in this interval succeeded. Interval of days are retrieved as start_date and end_date.

Order result by start_date.

The query result format is in the following example:

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Failed table:
+-------------------+
| fail_date         |
+-------------------+
| 2018-12-28        |
| 2018-12-29        |
| 2019-01-04        |
| 2019-01-05        |
+-------------------+

Succeeded table:
+-------------------+
| success_date      |
+-------------------+
| 2018-12-30        |
| 2018-12-31        |
| 2019-01-01        |
| 2019-01-02        |
| 2019-01-03        |
| 2019-01-06        |
+-------------------+

Result table:
+--------------+--------------+--------------+
| period_state | start_date   | end_date     |
+--------------+--------------+--------------+
| succeeded    | 2019-01-01   | 2019-01-03   |
| failed       | 2019-01-04   | 2019-01-05   |
| succeeded    | 2019-01-06   | 2019-01-06   |
+--------------+--------------+--------------+

The report ignored the system state in 2018 as we care about the system in the period 2019-01-01 to 2019-12-31.
From 2019-01-01 to 2019-01-03 all tasks succeeded and the system state was "succeeded".
From 2019-01-04 to 2019-01-05 all tasks failed and system state was "failed".
From 2019-01-06 to 2019-01-06 all tasks succeeded and system state was "succeeded".
``````

## MySQL Solution

``````1
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select 'succeeded' as period_state, min(success_date) as start_date,
max(success_date) as end_date
from (select success_date, row_number() over(order by success_date) as row_num
from Succeeded
where success_date between '2019-01-01' and '2019-12-31') t
group by dayofyear(success_date) - row_num

union

select 'failed' as period_state, min(fail_date) as start_date,
max(fail_date) as end_date
from (select fail_date, row_number() over(order by fail_date) as row_num
from Failed
where fail_date between '2019-01-01' and '2019-12-31') t
group by dayofyear(fail_date) - row_num

order by start_date
``````