PostgreSQL的：使用子查询的缩写（ 'AS'）在WHERE子句中

Question

考虑PostgreSQL的以下查询：

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，据我所知，我只能这样做：

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

哪个笨拙，代码复制，breaking the single-choice principle和完全丑陋。

顺便说一句，同样的问题适用于SELECT子句：我无法对以前定义的子查询使用缩写。

Answer 1

你可以使用子查询：

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做到这一点。