数据库面试题，求大脚给个标准答案

oracle 数据库
两张表结构如下：

部门表 department

部门编码

Code

部门名称

Name

人员表 employee

人员编码

Code

人员姓名

Name

所在部门

Dept_code
1)​ 写出sql语句，查询出所有的人员信息，具体展示信息如下：
人员编码 人员姓名 所在部门名称
2)​ 写出sql语句，查询出空编制的部门，具体的展示信息如下：
部门编码 部门名称
3)​ 写出sql语句，查询出部门的人员统计信息，具体的展示信息如下：
部门编码 部门名称 部门员工人数

写错了纠正下~
1)

SELECT a.Code,a.Name,b.Name 
FROM employee AS a LEFT JOIN department AS b ON a.Dept_code= b.Code

2)

SELECT Code,Name FROM department 
where Code NOT IN (
   SELECT Dept_code FROM employee)

3)

SELECT a.Code,a.Name,IFNULL(b.cnt ,0) 
FROM department AS a LEFT JOIN 
  (SELECT Dept_code, COUNT(*) AS cnt FROM employee GROUP BY Dept_code) AS b 
ON a.Code=b.Dept_code
    ```

1.SELECT a.Code,a.Name,b.Name FROM employee AS a INNER JOIN department AS b ON a.Dept_code= b.Code；

1)

SELECT a.Code,a.Name,b.Name 
FROM employee AS a LEFT JOIN department AS b ON a.Dept_code= b.Code

2)

SELECT Code,Name FROM department 
where Code NOT IN (
   SELECT Code FROM employee)

3)

SELECT a.Code,a.Name,IFNULL(b.cnt ,0) 
FROM department AS a LEFT JOIN 
  (SELECT Dept_code, COUNT(*) FROM employee GROUP BY Dept_code) AS b