feat: add solutions to lc problems: No.2668,2669

* No.2668.Find Latest Salaries
* No.2669.Count Artist Occurrences On Spotify Ranking List

Author: yanglbme

solution/2600-2699/2668.Find Latest Salaries/README.md

@@ -80,7 +80,19 @@ Each row contains employees details and their yearly salaries, however, some of
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```sql
-
+# Write your MySQL query statement below
+SELECT
+	emp_id,
+	firstname,
+	lastname,
+	max( salary ) AS salary,
+	department_id 
+FROM
+	Salary 
+GROUP BY
+	emp_id 
+ORDER BY
+	emp_id;
 ```
 
 <!-- tabs:end -->

solution/2600-2699/2668.Find Latest Salaries/README_EN.md

@@ -74,7 +74,19 @@ Each row contains employees details and their yearly salaries, however, some of
 ### **SQL**
 
 ```sql
-
+# Write your MySQL query statement below
+SELECT
+	emp_id,
+	firstname,
+	lastname,
+	max( salary ) AS salary,
+	department_id 
+FROM
+	Salary 
+GROUP BY
+	emp_id 
+ORDER BY
+	emp_id;
 ```
 
 <!-- tabs:end -->

solution/2600-2699/2668.Find Latest Salaries/Solution.sql

@@ -0,0 +1,13 @@
+# Write your MySQL query statement below
+SELECT
+	emp_id,
+	firstname,
+	lastname,
+	max( salary ) AS salary,
+	department_id 
+FROM
+	Salary 
+GROUP BY
+	emp_id 
+ORDER BY
+	emp_id;

solution/2600-2699/2669.Count Artist Occurrences On Spotify Ranking List/README.md

@@ -64,7 +64,17 @@ Each row contains an id, track_name, and artist.
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```sql
-
+# Write your MySQL query statement below
+SELECT
+	artist,
+	count( 1 ) AS occurrences 
+FROM
+	Spotify 
+GROUP BY
+	artist 
+ORDER BY
+	occurrences DESC,
+	artist;
 ```
 
 <!-- tabs:end -->

solution/2600-2699/2669.Count Artist Occurrences On Spotify Ranking List/README_EN.md

@@ -58,7 +58,17 @@ Each row contains an id, track_name, and artist.
 ### **SQL**
 
 ```sql
-
+# Write your MySQL query statement below
+SELECT
+	artist,
+	count( 1 ) AS occurrences 
+FROM
+	Spotify 
+GROUP BY
+	artist 
+ORDER BY
+	occurrences DESC,
+	artist;
 ```
 
 <!-- tabs:end -->

solution/2600-2699/2669.Count Artist Occurrences On Spotify Ranking List/Solution.sql

@@ -0,0 +1,11 @@
+# Write your MySQL query statement below
+SELECT
+	artist,
+	count( 1 ) AS occurrences 
+FROM
+	Spotify 
+GROUP BY
+	artist 
+ORDER BY
+	occurrences DESC,
+	artist;