feat: add sql solution to lc problem: No.1107

No.1107: New Users Daily Count

Author: yanglbme

solution/1100-1199/1107.New Users Daily Count/README.md

@@ -66,7 +66,16 @@ ID 为 5 的用户第一次登陆于 2019-03-01，因此他不算在 2019-06-21
 ### **SQL**
 
 ```sql
-
+# Write your MySQL query statement below
+SELECT
+	login_date,
+	count( user_id ) AS user_count 
+FROM
+	( SELECT min( activity_date ) AS login_date, user_id FROM Traffic WHERE activity = 'login' GROUP BY user_id ) t 
+WHERE
+	DATEDIFF( '2019-6-30', login_date ) <= 90 
+GROUP BY
+	login_date;
 ```
 
 <!-- tabs:end -->

solution/1100-1199/1107.New Users Daily Count/README_EN.md

@@ -70,7 +70,16 @@ The user with id 5 first logged in on 2019-03-01 so he's not counted on 2019
 ### **SQL**
 
 ```sql
-
+# Write your MySQL query statement below
+SELECT
+	login_date,
+	count( user_id ) AS user_count 
+FROM
+	( SELECT min( activity_date ) AS login_date, user_id FROM Traffic WHERE activity = 'login' GROUP BY user_id ) t 
+WHERE
+	DATEDIFF( '2019-6-30', login_date ) <= 90 
+GROUP BY
+	login_date;
 ```
 
 <!-- tabs:end -->

solution/1100-1199/1107.New Users Daily Count/Solution.sql

@@ -0,0 +1,10 @@
+# Write your MySQL query statement below
+SELECT
+	login_date,
+	count( user_id ) AS user_count 
+FROM
+	( SELECT min( activity_date ) AS login_date, user_id FROM Traffic WHERE activity = 'login' GROUP BY user_id ) t 
+WHERE
+	DATEDIFF( '2019-6-30', login_date ) <= 90 
+GROUP BY
+	login_date;