Shulou(Shulou.com)06/01 Report--

Sort query

Syntax:

Select query Field 1

From table

Where [filter criteria]

Order by to sort fields 2 asc ascending, desc descending, and fields 3 asc ascending and desc descending

If you don't write, it defaults to ascending order.

Case: query employee information and require wages to be sorted from high to low

SELECT * FROM employeesORDER BY salary DESC

# case 2: query department number > = 90, employee information in ascending order by entry date

SELECT * FROM employeesWHERE department_id > = 90ORDER BY hiredate ASC

# case: sort by expression, such as showing annual salary by annual salary

SELECT salary*12* (1+IFNULL (commission_pct,0)) FROM employeesORDER BY salary*12* (1+IFNULL (commission_pct,0)) DESC

# case: alias the sort field, and then sort by alias

SELECT salary*12* (1+IFNULL (commission_pct,0)) AS Annual salary FROM employeesORDER BY Annual salary ASC

# case: displays the employee's name and salary in descending order by name length (sorted by function)

SELECT LENGTH ('aaaa'); # shows a length of 4

SELECT LENGTH (last_name) AS byte length, last_name, salaryFROM employeesORDER BY LENGTH (last_name) DESC

# case: to query employee information, it is required to sort by salary first, and then by employee number, (sort by multiple fields)

SELECT * FROM employeesORDER BY salary ASC,employee_id DESC

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