mysql subquery Case

Employee names and salaries # queries and the same sector Zlotkey

SELECT last_name,salary
FROM employees
WHERE department_id=(
    SELECT department_id
    FROM employees
    WHERE last_name='Zlotkey'
);

# Query higher wages than the company average wage of employees employee number, name and salary

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

# Query various departments in this sector wages higher than the average salary of the employee number, name and salary
Note: Connect Employees table and the average payroll, rescreening

SELECT employee_id,last_name,salary
FROM (
    SELECT AVG(salary) s,department_id
    FROM employees 
    GROUP BY department_id
) a
INNER JOIN employees e
ON a.department_id=e.department_id
WHERE e.salary>s;

# Query name contains the letters u and staff employees of the same department employee number and name
to the query contains u id department employees, as in the case then check id

SELECT employee_id,last_name
FROM employees
WHERE department_id IN(
    SELECT DISTINCT department_id
    FROM employees
    WHERE last_name LIKE '%u%'
);

# Location_id sector inquiry in 1700 for the department's employees number of employees
Note first check location_id department number is equal to 1700, the number of employees in the query

SELECT employee_id
FROM employees e
WHERE e.`department_id` IN(
    SELECT department_id
    FROM departments d
    WHERE d.`location_id`=1700
)

# Query manager is K_ing employee names and salaries, there are two K_ing

SELECT last_name,salary
FROM employees e
WHERE e.manager_id IN(
    SELECT `employee_id`
    FROM employees m
    WHERE `last_name`='K_ing'
);

# Query the name of the highest wages, the requirements first_ame and last_name displayed as a column called the family name. Name
# surnamed special characters that require quotes

SELECT CONCAT(first_name,last_name) '姓.名'  
FROM employees e
WHERE e.salary=(
    SELECT MAX(salary)
    FROM employees
);

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