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#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
);

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

#习题：返回公司员工工资最少的员工的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manger_id和department_id相同的其他员工的empioyee-id,marger_id,department_id

#方式一
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;
SELECT manager_id
FROM employees
WHERE employee_id = 141;
SELECT department_id
FROM employees
WHERE employee_id = 141;
#方式二
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110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 = 110
);

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

#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
);