PostgreSQL的：使用子查詢的縮寫（ 'AS'）在WHERE子句中

Question

考慮PostgreSQL的以下查詢：

SELECT 
    a, b, 
    (A VERY LONG AND COMPLICATED SUBQUERY) AS c, 
    (ANOTHER VERY LONG AND COMPLICATED SUBQUERY) AS d 
FROM table 

我想有WHERE子句中c和d，如：

WHERE c AND d; 

但是，據我所知，我只能這樣做：

WHERE A VERY LONG AND COMPLICATED SUBQUERY) AND 
    (ANOTHER VERY LONG AND COMPLICATED SUBQUERY) 

哪個笨拙，代碼複製，breaking the single-choice principle和完全醜陋。

順便說一句，同樣的問題適用於SELECT子句：我無法對以前定義的子查詢使用縮寫。

Answer 1

你可以使用子查詢：

SELECT a,b,c,d FROM 
    (SELECT 
     a, b, 
     (A VERY LONG AND COMPLICATED SUBQUERY) AS c, 
     (ANOTHER VERY LONG AND COMPLICATED SUBQUERY) AS d 
     FROM table 
    ) AS T1 
WHERE c AND d 

你也可以用CTE做到這一點。