How does php mysql get the number of orders per day, 7 days a week?

question 1:
1, the array of $array is as follows:

array (size=7)
  1 => string "2018-09-21" (length=10)
  2 => string "2018-09-22" (length=10)
  3 => string "2018-09-23" (length=10)
  4 => string "2018-09-24" (length=10)
  5 => string "2018-09-25" (length=10)
  6 => string "2018-09-26" (length=10)
  7 => string "2018-09-27" (length=10)

The array of

2 and $list is as follows:

array (size=3)
  0 => 
    array (size=2)
      "riqi" => string "2018-09-21" (length=10)
      "count" => int 2
  1 => 
    array (size=2)
      "riqi" => string "2018-09-26" (length=10)
      "count" => int 2
  2 => 
    array (size=2)
      "riqi" => string "2018-09-27" (length=10)
      "count" => int 3

ask for help: how to php achieve the following effects

array (size=3)
  0 => 
    array (size=2)
      "riqi" => string "2018-09-21" (length=10)
      "count" => int 2
  1 => 
    array (size=2)
      "riqi" => string "2018-09-22" (length=10)
      "count" => int 0
  2 => 
    array (size=2)
      "riqi" => string "2018-09-23" (length=10)
      "count" => int 0
  3 => 
    array (size=2)
      "riqi" => string "2018-09-24" (length=10)
      "count" => int 0
  4 => 
    array (size=2)
      "riqi" => string "2018-09-25" (length=10)
      "count" => int 0
  5 => 
    array (size=2)
      "riqi" => string "2018-09-26" (length=10)
      "count" => int 2
  6 => 
    array (size=2)
      "riqi" => string "2018-09-27" (length=10)
      "count" => int 3

< hr >

question 2:
the existing sql is as follows:

select FROM_UNIXTIME(addtime,"%Y-%m-%d") as riqi, count(1) as count from order where FROM_UNIXTIME(addtime,"%Y-%m-%d") >= now() - interval 7 day group by FROM_UNIXTIME(addtime,"%Y-%m-%d")

how to achieve the following effects with one sentence of sql

array (size=3)
  0 => 
    array (size=2)
      "riqi" => string "2018-09-21" (length=10)
      "count" => int 2
  1 => 
    array (size=2)
      "riqi" => string "2018-09-22" (length=10)
      "count" => int 0
  2 => 
    array (size=2)
      "riqi" => string "2018-09-23" (length=10)
      "count" => int 0
  3 => 
    array (size=2)
      "riqi" => string "2018-09-24" (length=10)
      "count" => int 0
  4 => 
    array (size=2)
      "riqi" => string "2018-09-25" (length=10)
      "count" => int 0
  5 => 
    array (size=2)
      "riqi" => string "2018-09-26" (length=10)
      "count" => int 2
  6 => 
    array (size=2)
      "riqi" => string "2018-09-27" (length=10)
      "count" => int 3

Mysql php

Jul.20,2021