按城市定义自定义订单

Question

我试图定义一个自定义ORDERY BY城市。

事情是这样的：

New York (255) 
Paris (26) 
Vien(15) 

然后ORDER BY city ASC。

我试过这个查询，这是行不通的：

SELECT count(id_item) as q, city FROM item GROUP BY city ORDER BY FIELD(city,'New York','Paris','Vien'), city ASC 

Answer 1

你可以做这样的事情：

SELECT 
    count(id_item) as q, 
    city 
FROM 
    item 
GROUP BY 
    city 
ORDER BY 
    ( 
     CASE 
      WHEN city='New York' THEN 1 
      WHEN city='Paris' THEN 2 
      WHEN city='Vien' THEN 3 
      ELSE 4 
     END 
    ) ASC, 
    city ASC 

Answer 2

可以order by city='New York' desc, city='Paris' desc, city='Vien' desc, city

甚至order by city in ('New York', 'Paris', 'Vien') desc, city因为这些3已按字母顺序排列

Answer 3

ORDER BY关键字默认按升序排列记录。要按降序对记录进行排序，可以使用DESC关键字。试试这个 -

SELECT count(id_item) as q, city FROM item GROUP BY city ORDER BY city; 

对于降，你可以做这样的事情 -

SELECT count(id_item) as q, city FROM item GROUP BY city ORDER BY city DESC; 

取得与自己的优先顺序行，SELECT查询将如下：

SELECT 
    count(id_item) as q, 
    city 
FROM 
    item 
GROUP BY 
    city 
ORDER BY 
    ( 
     CASE 
      WHEN city='New York' THEN 1 
      WHEN city='Paris' THEN 2 
      WHEN city='Vien' THEN 3 
      ELSE 4 
     END 
    ) ASC, 
    city ASC