Sort query

Sort query ：SELECT Query list FROM surface WHERE filter ORDER BY Sort list (ASC/DESC)
AEC/DESC = Ascending / Descending , The default is ascending
ORDER BY Support Single field 、 Multiple fields 、 expression 、 function 、 Alias

Sort by a single field

#1.  Query employee information , We need to rank wages from high to low 
SELECT *
FROM employees
ORDER BY salary DESC

#2.  Query department number is greater than or equal to 90 Employee information , Sort them by the time they are employed 
SELECT *
FROM employees
WHERE department_id >= 90
ORDER BY hiredate ASC

By expression / Alias sort

#3.  Display employee information and annual salary according to the level of annual salary 【 Sort by expression 】
SELECT *,salary*12*(1+IFNULL(commission_pct,0)) AS " Annual salary "
FROM employees
ORDER BY " Annual salary " DESC

Sort by function

#4.  Display the employee's name and salary according to the length of the name 【 Sort by function 】
SELECT LENGTH(last_name) AS " bytes ",last_name,salary
FROM employees
ORDER BY LENGTH(last_name) DESC

Sort by multiple fields

#5.  Query employee information , It is required to be in ascending order of salary first , In descending order by employee number 【 Sort by multiple fields 】
SELECT *
FROM employees
ORDER BY salary ASC,employee_id DESC