如何查询select生成的表？

Question

举个例子:

SELECT name, address, phone FROM USER;

生成表格

name | address | phone 
...  |   ...   |  ...

如何使用此表生成另一个查询？

例如:

SELECT count(address) FROM (SELECT name, address, phone, from user);

我知道这不是最好的例子,但有没有办法做到这一点？

Answer 1

使用相同的语法,但为派生表提供别名

SELECT count(subadd.address) 
FROM (SELECT name, address, phone, from user) as subadd;