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feat: add sql solutions to lc problems (doocs#1201)
* No.1127.User Purchase Platform * No.1132.Reported Posts II * No.1141.User Activity for the Past 30 Days I * No.1142.User Activity for the Past 30 Days II * No.1148.Article Views I * No.1149.Article Views II * No.1158.Market Analysis I
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‎solution/1100-1199/1127.User Purchase Platform/README.md‎

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```sql
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# Write your MySQL query statement below
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WITH
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s AS (
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P AS (
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SELECT DISTINCT spend_date, 'desktop' AS platform FROM Spending
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UNION
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SELECT DISTINCT spend_date, 'mobile' AS platform FROM Spending
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SELECT DISTINCT spend_date, 'mobile' FROM Spending
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UNION
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SELECT DISTINCT spend_date, 'both' AS platform FROM Spending
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SELECT DISTINCT spend_date, 'both' FROM Spending
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),
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t AS (
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T AS (
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SELECT
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user_id,
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spend_date,
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if(count(platform) = 2, 'both', platform) AS platform,
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sum(amount) AS amount
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sum(amount) AS amount,
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if(count(platform) = 1, platform, 'both') AS platform
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FROM Spending
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GROUP BY 1, 2
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)
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SELECT
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t1.*,
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p.*,
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ifnull(sum(amount), 0) AS total_amount,
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count(t2.user_id) AS total_users
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count(t.user_id) AS total_users
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FROM
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s AS t1
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LEFT JOIN t AS t2 USING (spend_date, platform)
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P AS p
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LEFT JOIN T AS t USING (spend_date, platform)
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GROUP BY 1, 2;
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```
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‎solution/1100-1199/1127.User Purchase Platform/README_EN.md‎

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```sql
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# Write your MySQL query statement below
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WITH
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s AS (
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P AS (
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SELECT DISTINCT spend_date, 'desktop' AS platform FROM Spending
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UNION
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SELECT DISTINCT spend_date, 'mobile' AS platform FROM Spending
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SELECT DISTINCT spend_date, 'mobile' FROM Spending
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UNION
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SELECT DISTINCT spend_date, 'both' AS platform FROM Spending
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SELECT DISTINCT spend_date, 'both' FROM Spending
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),
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t AS (
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T AS (
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SELECT
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user_id,
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spend_date,
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if(count(platform) = 2, 'both', platform) AS platform,
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sum(amount) AS amount
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sum(amount) AS amount,
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if(count(platform) = 1, platform, 'both') AS platform
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FROM Spending
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GROUP BY 1, 2
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)
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SELECT
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t1.*,
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p.*,
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ifnull(sum(amount), 0) AS total_amount,
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count(t2.user_id) AS total_users
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count(t.user_id) AS total_users
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FROM
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s AS t1
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LEFT JOIN t AS t2 USING (spend_date, platform)
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P AS p
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LEFT JOIN T AS t USING (spend_date, platform)
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GROUP BY 1, 2;
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```
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‎solution/1100-1199/1127.User Purchase Platform/Solution.sql‎

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# Write your MySQL query statement below
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WITH
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s AS (
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P AS (
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SELECT DISTINCT spend_date, 'desktop' AS platform FROM Spending
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UNION
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SELECT DISTINCT spend_date, 'mobile' AS platform FROM Spending
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SELECT DISTINCT spend_date, 'mobile' FROM Spending
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UNION
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SELECT DISTINCT spend_date, 'both' AS platform FROM Spending
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SELECT DISTINCT spend_date, 'both' FROM Spending
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),
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t AS (
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T AS (
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SELECT
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user_id,
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spend_date,
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if(count(platform) = 2, 'both', platform) AS platform,
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sum(amount) AS amount
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sum(amount) AS amount,
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if(count(platform) = 1, platform, 'both') AS platform
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FROM Spending
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GROUP BY 1, 2
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)
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SELECT
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t1.*,
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p.*,
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ifnull(sum(amount), 0) AS total_amount,
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count(t2.user_id) AS total_users
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count(t.user_id) AS total_users
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FROM
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s AS t1
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LEFT JOIN t AS t2 USING (spend_date, platform)
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P AS p
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LEFT JOIN T AS t USING (spend_date, platform)
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GROUP BY 1, 2;

‎solution/1100-1199/1132.Reported Posts II/README.md‎

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```sql
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# Write your MySQL query statement below
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SELECT
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round(avg(avg_per * 100), 2) AS average_daily_percent
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FROM
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(
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WITH
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T AS (
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SELECT
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count(DISTINCT t2.post_id) / count(DISTINCT t1.post_id) AS avg_per
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count(DISTINCT t2.post_id) / count(
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DISTINCT t1.post_id
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) * 100 AS percent
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FROM
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Actions AS t1
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LEFT JOIN Removals AS t2 ON t1.post_id = t2.post_id
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WHERE t1.extra = 'spam'
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WHERE extra = 'spam'
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GROUP BY action_date
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) AS t3;
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)
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SELECT round(avg(percent), 2) AS average_daily_percent
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FROM T;
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```
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<!-- tabs:end -->

‎solution/1100-1199/1132.Reported Posts II/README_EN.md‎

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```sql
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# Write your MySQL query statement below
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SELECT
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round(avg(avg_per * 100), 2) AS average_daily_percent
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FROM
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(
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WITH
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T AS (
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SELECT
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count(DISTINCT t2.post_id) / count(DISTINCT t1.post_id) AS avg_per
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count(DISTINCT t2.post_id) / count(
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DISTINCT t1.post_id
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) * 100 AS percent
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FROM
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Actions AS t1
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LEFT JOIN Removals AS t2 ON t1.post_id = t2.post_id
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WHERE t1.extra = 'spam'
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WHERE extra = 'spam'
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GROUP BY action_date
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) AS t3;
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)
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SELECT round(avg(percent), 2) AS average_daily_percent
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FROM T;
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```
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<!-- tabs:end -->

‎solution/1100-1199/1132.Reported Posts II/Solution.sql‎

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# Write your MySQL query statement below
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SELECT
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round(avg(avg_per * 100), 2) AS average_daily_percent
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FROM
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(
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WITH
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T AS (
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SELECT
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count(DISTINCT t2.post_id) / count(DISTINCT t1.post_id) AS avg_per
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count(DISTINCT t2.post_id) / count(
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DISTINCT t1.post_id
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) * 100 AS percent
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FROM
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Actions AS t1
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LEFT JOIN Removals AS t2 ON t1.post_id = t2.post_id
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WHERE t1.extra = 'spam'
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WHERE extra = 'spam'
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GROUP BY action_date
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) AS t3;
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)
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SELECT round(avg(percent), 2) AS average_daily_percent
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FROM T;

‎solution/1100-1199/1141.User Activity for the Past 30 Days I/README.md‎

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<!-- 这里可写通用的实现逻辑 -->
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**方法一：GROUP BY + HAVING**
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我们查询出所有在 `2019-07-27` 且在 $30$ 天内的所有活动记录，然后按照日期分组，统计每天的去重活跃用户数。
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<!-- tabs:start -->
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### **SQL**
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```sql
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SELECT
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activity_date AS day,
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COUNT(DISTINCT user_id) AS active_users
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# Write your MySQL query statement below
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SELECT activity_date AS day, count(DISTINCT user_id) AS active_users
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FROM Activity
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WHERE
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DATEDIFF('2019-07-27', activity_date) >= 0
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AND DATEDIFF('2019-07-27', activity_date) < 30
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GROUP BY activity_date;
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activity_date <= '2019-07-27'
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AND datediff('2019-07-27', activity_date) < 30
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GROUP BY 1;
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```
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<!-- tabs:end -->

‎solution/1100-1199/1141.User Activity for the Past 30 Days I/README_EN.md‎

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### **SQL**
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```sql
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SELECT
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activity_date AS day,
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COUNT(DISTINCT user_id) AS active_users
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# Write your MySQL query statement below
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SELECT activity_date AS day, count(DISTINCT user_id) AS active_users
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FROM Activity
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WHERE
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DATEDIFF('2019-07-27', activity_date) >= 0
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AND DATEDIFF('2019-07-27', activity_date) < 30
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GROUP BY activity_date;
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activity_date <= '2019-07-27'
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AND datediff('2019-07-27', activity_date) < 30
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GROUP BY 1;
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```
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<!-- tabs:end -->

‎solution/1100-1199/1141.User Activity for the Past 30 Days I/Solution.sql‎

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SELECT
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activity_date AS day,
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COUNT(DISTINCT user_id) AS active_users
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# Write your MySQL query statement below
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SELECT activity_date AS day, count(DISTINCT user_id) AS active_users
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FROM Activity
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WHERE
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DATEDIFF('2019-07-27', activity_date) >= 0
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AND DATEDIFF('2019-07-27', activity_date) < 30
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GROUP BY activity_date;
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activity_date <= '2019-07-27'
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AND datediff('2019-07-27', activity_date) < 30
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GROUP BY 1;

‎solution/1100-1199/1142.User Activity for the Past 30 Days II/README.md‎

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```sql
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# Write your MySQL query statement below
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SELECT
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IFNULL(
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ROUND(COUNT(DISTINCT session_id) / COUNT(DISTINCT user_id), 2),
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0
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) AS average_sessions_per_user
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FROM Activity
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WHERE
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DATEDIFF('2019-07-27', activity_date) >= 0
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AND DATEDIFF('2019-07-27', activity_date) < 30;
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WITH
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T AS (
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SELECT
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count(DISTINCT session_id) AS sessions
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FROM Activity
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WHERE
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activity_date <= '2019-07-27'
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AND datediff('2019-07-27', activity_date) < 30
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GROUP BY user_id
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)
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SELECT ifnull(round(avg(sessions), 2), 0) AS average_sessions_per_user
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FROM T;
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```
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<!-- tabs:end -->

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