重用WHERE-Clause中Select表达式的子查询 [英] Reuse Subquery from Select Expression in WHERE-Clause

问题描述

当然不可能写

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

做到这一点的最佳方法是什么?

What is the best way to do this?

• SELECT (some subselect) FROM t WHERE (some subselect) = 'const'?
• 查看?
• 存储的功能?
• 有没有?
• 其他?

• SELECT (some subselect) FROM t WHERE (some subselect) = 'const'?
• View?
• Stored Function?
• HAVING?
• other?

推荐答案

您可以将(some subselect)作为表移动到FROM中:

you can move (some subselect) as table in the FROM :

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

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