Postgresql：计算百分比，但铸造不会'；行不通

我在下面的查询中尝试对列进行算术运算。我已经根据postgres文档使用了正确的强制转换，但是（）但是有人仍然在我的bigint列中剪切结果，并避免在结果集中使用小数点

select * from (
    select (degree_one + degree_two) as degree_easy, 
        degree_three as degree_hard, 
        (((degree_one + degree_two)/(degree_one + degree_two + degree_three))::decimal) as easy_percent, ((degree_three/(degree_one + degree_two + degree_three))::decimal) as hard_percent from recommendation_degree
    ) as dc 
where dc.degree_easy >= 4 and dc.degree_hard >= 4

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我做错了什么？除了十进制，我还尝试了float和real，但它们都给出了相同的结果。

您可以尝试在除法中强制计算十进制值，否则我认为您将最终执行整数除法（然后将除法转换为十进制），结果将不正确

试试这个：

select * from (
  select (degree_one + degree_two) as degree_easy,
  degree_three as degree_hard,
  (degree_one::decimal + degree_two::decimal)/(degree_one::decimal + degree_two::decimal + degree_three::decimal) as easy_percent, 
  degree_three::decimal/(degree_one::decimal + degree_two::decimal + degree_three::decimal) as hard_percent 
  from recommendation_degree
    ) as dc 
where dc.degree_easy >= 4 and dc.degree_hard >= 4

可能没有必要同时计算除数和除数，我认为当只计算除数时，它应该会起作用

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实际按照我想要的方式使用x:：real work。我用了你的符号，但把小数换成了实数。