如何按類型排序 - SQL

Question

我與排序由flag_color查詢工作，但顏色我希望它的優先級：

此查詢現在返回：

SELECT flag_color as color 
FROM  clinic_performance_flags 
GROUP BY clinic_user_id 
ORDER BY flag_color ASC 

green 
green 
green 
green 
red 
red 
red 
red 
yellow 
yellow 
yellow 

但是我想改變順序，所以順序變成（red應該永遠是第一個，yellow秒和​​第三個）示例：

red 
red 
red 
red 
yellow 
yellow 
yellow 
yellow 
green 
green 
green 
green 

Answer 1

使用CASE在ORDER BY：

SELECT flag_color as color 
FROM  clinic_performance_flags 
GROUP BY clinic_user_id 
ORDER BY CASE WHEN flag_color = 'red' THEN 1 
       WHEN flag_color = 'yellow' THEN 2 
       WHEN flag_color = 'green' THEN 3 
             ELSE 4 
     END, flag_color ASC 

Answer 2

使用FIELD函數。

SELECT flag_color AS color 
FROM clinic_performance_flags 
GROUP BY clinic_user_id 
ORDER BY FIELD(flag_color ,'red','yellow','green'), flag_color ASC 

Answer 3

你可以使用一個CASE語句

SELECT flag_color as color 
FROM  clinic_performance_flags 
GROUP BY clinic_user_id 
ORDER BY CASE WHEN flag_color = 'red' THEN 1 
       WHEN flag_color = 'yellow' THEN 2 
       WHEN flag_color = 'green' THEN 3 
       ELSE 4 END