exercises bug fixed

data/2.MySQL中阶/5.子查询/5. IN/in.md

@@ -54,7 +54,7 @@ from employee
 where dept in ('dev' and 'hr');
 ```
 
-#### D
+### D
 
 ```sql
 select id, dept, name, post 

data/2.MySQL中阶/6.连接查询/2. LEFT JOIN/left_join.md

@@ -66,7 +66,7 @@ from department as d
          cross join employee as e on e.dept = d.id
 where e.post = 'assistant'
 ```
- 
+
 ### D
 
 ```sql