Sort mysql query field

Sort query
syntax:

select query field 1
from the table
where [Filters]
order by 2 asc field you want to sort in ascending, desc descending to ascending row field 3 asc, desc descending order
if you do not write the default is ascending

Case: query employee information, salary requirements listed in the order

SELECT 
    *
FROM 
    employees
ORDER BY salary DESC;

Case # 2: Query department number> = 90, according to the entry date in ascending order of employee information

SELECT
    *
FROM
    employees
WHERE
    department_id >=90
ORDER BY hiredate ASC;

Case #: Sort by expressions, such as by showing annual salary level

SELECT
    salary*12*(1+IFNULL(commission_pct,0))
FROM
    employees
ORDER BY salary*12*(1+IFNULL(commission_pct,0)) DESC;

# Case: the sort field aliases, and then sorted by Alias

SELECT
    salary*12*(1+IFNULL(commission_pct,0)) AS 年薪
FROM 
    employees
ORDER BY 
    年薪 ASC;

Case #: display in descending order according to the length of the name of the employee names and salaries (ordered function)
the SELECT LENGTH ( 'aaaa'); # display length of 4

SELECT
    LENGTH(last_name) AS 字节长度,
    last_name,
    salary
FROM 
    employees
ORDER BY 
    LENGTH(last_name) DESC;

Case #: query employee information, press the required wage sorted, then sort the employee number, (sort by multiple fields)

SELECT
    *
FROM
    employees
ORDER BY
    salary ASC,employee_id DESC;