更新 'mysql-MD/第二章：数据库管理及数据类型.md'

mysql-MD/第二章：数据库管理及数据类型.md

@@ -426,11 +426,11 @@ ERROR 1062 (23000): Duplicate entry 'xingdian' for key 'dept_name'
 
 ```shell
 MySQL [(none)]> create table school.student6(
-    ->     id int primary key not null auto_increment,
+     id int primary key not null auto_increment,
-    ->     name varchar(50) not null,
+     name varchar(50) not null,
-    ->     sex enum('male','female') not null default 'male', 
+    sex enum('male','female') not null default 'male', 
-    ->     age int not null default 18
+     age int not null default 18
-    ->     );
+     );
 Query OK, 0 rows affected (0.47 sec)
 ```