[打卡]郭佳豪，子查询-习题

# 单行子查询

# 单行操作符 = != <> > >= < <=

# 习题：查询工资大于149号员工工资的员工信息

SELECT employee_id,last_name,salary
FROM employees
WHERE salary>(
SELECT salary
FROM employees
WHERE employee_id = 149
);

#习题：返回job_id与141号员工相同，salary比143号员工多的员工姓名，job_id和工资

SELECT last_name,job_id,salary
FROM employees
WHERE job_id=(
SELECT job_id
FROM employees
WHERE employee_id = 141
)
AND salary>(
SELECT salary
FROM employees
WHERE employee_id = 143
);

# 中英互换

# 习题：返回公司工资最少的员工的last_name,job_id和salary

SELECT last_name,job_id,salary
FROM employees
WHERE salary = (
SELECT MIN(salary)
FROM employees
);

/*

子查询编写技巧（步骤）

1 从里往外写

2 从外往里写

*/

# 习题：查询与141号员工的manager_id和department_id相同的其他员工的employee_id,manager_id,department_id

#方式1

SELECT employee_id,manager_id,department_id
FROM employees
WHERE manager_id = (
SELECT manager_id
FROM employees
WHERE employee_id = 141
)
AND department_id = (
SELECT department_id
FROM employees
WHERE employee_id = 141
)
AND employee_id != 141;

# 方式2

SELECT employee_id,manager_id,department_id
FROM employees
WHERE (manager_id,department_id) = (
SELECT manager_id,department_id
FROM employees
WHERE employee_id = 141
)
AND employee_id != 141;

# 习题：查询最低工资大于60号部门最低工资的部门id和其最低工资

SELECT department_id,MIN(salary)
FROM employees
GROUP BY department_id
HAVING MIN(salary) >(
SELECT MIN(salary)
FROM employees
WHERE department_id = 60
)
AND department_id IS NOT NULL;

# 非法使用子查询

SELECT employee_id,last_name
FROM employees
WHERE salary = (
SELECT MIN(salary)
FROM employees
GROUP BY department_id
);