Question

我需要显示一个没有指定主管在同一部门工作的员工名单

Table: employee
Fields:
id INT(pk),
department_id INT,
chief_id INT,
name Varchar(100),
salary INT

查询：

SELECT One.name AS Employee,One.department_id, Two.name AS Chief, Two.department_id

FROM employee One, employee Two

WHERE (One.chief_id = Two.id AND One.department_id != Two.department_id) OR One.department_id IS NULL;

Answer 1

SELECT One.name AS Employee,One.department_id, Two.name AS Chief,  Two.department_id
FROM employee One
LEFT JOIN employee two ON One.chief_id = Two.id
WHERE NOT EXISTS (
                 SELECT 0 FROM employee two 
                     where One.department_id = Two.department_id 
                            AND One.chief_id = Two.id
                )

Answer 2

尝试以下内容;）

SELECT One.name AS Employee,One.department_id, Two.name AS Chief, Two.department_id
FROM employee One, employee Two
WHERE One.chief_id = Two.id AND (One.department_id IS NULL OR One.department_id <> Two.department_id);

Answer 3

以下查询可能会提供所需的结果： -

SQL SERVER ： -

1, product1, content1, 10
2, product2, content2, 30
3, product1, content3, 20
4, product3, content4, 0
5, product2, content5, 35
6, product3, content6, 0

MYSQL ： -

SELECT One.name AS Employee,One.department_id, Two.name AS Chief, Two.department_id
FROM employee One, employee Two
WHERE (One.chief_id = Two.id AND One.department_id != Two.department_id) OR ISNULL(One.department_id,0)=0;

Answer 4

尝试查询

SELECT 
  Two.name AS Employee,
  Two.department_id AS Employee_Dept,
  One.name AS Chief_Name,
  One.department_id AS Chif_Dept 
FROM
  employee ONE 
  INNER JOIN employee Two 
    ON One.id = Two.chief_id 
    AND One.department_id != Two.department_id ;

为什么SQL查询SELECT不返回IS NULL结果

4 个答案: