在WHERE-Clause中重用Select Expression中的子查询

Question

当然不可能写

SELECT (some subselect) AS blah FROM t WHERE blah = 'const'

做这个的最好方式是什么？

• SELECT (some subselect) FROM t WHERE (some subselect) = 'const'？
• 视图？
• 存储功能？
• HAVING？
• 其他？

Answer 1

你可以(some subselect)在表中移动FROM:

SELECT s.blah
  FROM t, (some subselect) s
 WHERE t.id = s.id
   AND s.blah = 'const'