通過在MYSQL中重新使用派生字段列名稱來簡化查詢字符串

Question

我們是否仍可以通過使用派生列作為另一個過程的輸入來簡化此查詢

$query = "SELECT   table1.id,
         COUNT(DISTINCT arr1.element) AS Arr1,
         COUNT(DISTINCT arr2.element) AS Arr2,
         COUNT(DISTINCT arr1.element) +
         COUNT(DISTINCT arr2.element) AS tot,
(COUNT(DISTINCT arr1.element)/(COUNT(DISTINCT arr1.element)+COUNT(DISTINCT arr2.element)))*col3 AS c31,
(COUNT(DISTINCT arr2.element)/(COUNT(DISTINCT arr1.element)+COUNT(DISTINCT arr2.element)))*col3 AS c32
FROM table1 
WHERE col2 = 'x'" 

像這樣的東西

$query = "SELECT   table1.id,
         COUNT(DISTINCT arr1.element) AS Arr1,
         COUNT(DISTINCT arr2.element) AS Arr2,
         COUNT(DISTINCT arr1.element) +
         COUNT(DISTINCT arr2.element) AS tot,
        (Arr1/tot)*col3 AS c31,
        (Arr2/tot)*col3 AS c32
FROM  table1 
WHERE col2 = 'x'" 

謝謝

Answer 1

您可以嘗試以下方法：

$query = "
SELECT tab.id, tab.Arr1, tab.Arr2, tab.tot, (tab.Arr1/tab.tot) as c31, (tab.Arr2/tab.tot) as c32
from (
SELECT   table1.id,
         COUNT(DISTINCT arr1.element) AS Arr1,
         COUNT(DISTINCT arr2.element) AS Arr2,
         COUNT(DISTINCT arr1.element) +
         COUNT(DISTINCT arr2.element) AS tot
FROM table1 
WHERE col2 = 'x'
) as 'tab' " 

Answer 2

嘗試這個：

SELECT id, Arr1, Arr2, (Arr1 + Arr2) tot, ((Arr1 / (Arr1 + Arr2)) * col3) c31, ((Arr2 / (Arr1 + Arr2)) * col3) c32
FROM (SELECT table1.id, COUNT(DISTINCT arr1.element) AS Arr1, COUNT(DISTINCT arr2.element) AS Arr2, col3
FROM table1 WHERE col2 = 'x') AS A