Upload 118

Author: ggeerraarrdd

README.md

@@ -146,6 +146,7 @@ To make the daily tasks of creating a new file and updating the index easier, th
 | 115   | [Immediate Food Delivery II](https://leetcode.com/problems/immediate-food-delivery-ii/description/)                                                           | [Solution](solutions/115_immediate_food_delivery_ii.md)                               | LeetCode    | Medium       |   |
 | 116   | [Game Play Analysis IV](https://leetcode.com/problems/game-play-analysis-iv/description/)                                                                     | [Solution](solutions/116_game_play_analysis_iv.md)                                    | LeetCode    | Medium       |   |
 | 117   | [Number of Unique Subjects Taught by Each Teacher](https://leetcode.com/problems/number-of-unique-subjects-taught-by-each-teacher/description/)               | [Solution](solutions/117_number_of_unique_subjects_taught_by_each_teacher.md)         | LeetCode    | Easy         |   |
+| 118   | [User Activity for the Past 30 Days I](https://leetcode.com/problems/user-activity-for-the-past-30-days-i/description/)                                       | [Solution](solutions/118_user_activity_for_the_past_30_days_i.md)                     | LeetCode    | Easy         | `BETWEEN`, `DATE` w/ `INTERVAL`  |
 
 ## Author(s)
 

solutions/118_user_activity_for_the_past_30_days_i.md

@@ -0,0 +1,46 @@
+# SQL Everyday \#118
+
+## User Activity for the Past 30 Days I
+
+Site: LeetCode\
+Difficulty per Site: Easy
+
+## Problem
+
+Write a solution to find the daily active user count for a period of `30` days ending `2019-07-27` inclusively. A user was active on someday if they made at least one activity on that day.
+
+Return the result table in *any order*. [[Full Description](https://leetcode.com/problems/user-activity-for-the-past-30-days-i/description/)]
+
+## Submitted Solution
+
+```sql
+-- Submitted Solution
+SELECT
+    activity_date AS day
+    ,COUNT(DISTINCT user_id) AS active_users
+FROM Activity
+WHERE activity_date BETWEEN DATE('2019-07-28' - INTERVAL 30 DAY) AND '2019-07-28' 
+GROUP BY activity_date
+;
+```
+
+## Site Solution
+
+```sql
+-- LeetCode Solution 
+SELECT 
+    activity_date AS day, 
+    COUNT(DISTINCT user_id) AS active_users
+FROM 
+    Activity
+WHERE 
+    DATEDIFF('2019-07-27', activity_date) < 30 AND DATEDIFF('2019-07-27', activity_date)>=0
+GROUP BY 1
+```
+
+## Notes
+
+TODO
+
+Go to [Table of Contents](/README.md#contents)\
+Go to [Overview](/README.md)