如何在 rails 范围内模拟 Postgresql EXCEPT 运算符？

Question

我有一个 SQL 查询

SELECT * FROM students
EXCEPT
SELECT * FROM students WHERE val->>'rating' = 'Fail'

如何在 Rails 范围内获得相同的结果？

Answer 1

SELECT * FROM students
EXCEPT
SELECT * FROM students WHERE val->>'rating' = 'Fail'

等于

Student.where("val->>'rating' IS DISTINCT FROM ?", 'Fail')

How to emulate Postgresql EXCEPT operator in rails scope?