如何计算PostgreSQL中的百分比（％）

Question

我无法计算PostgreSQL中的％ 在我的代码下方

let url = URL(string: "https://mywebsite.co.uk/loginarea.php?link=\(answer)")!

答案得到0和100而不是60％

Answer 1

投射为numeric的值

SELECT ROUND(( 3::NUMERIC/5::NUMERIC ) * 100);

Answer 2

如果需要浮点结果，则应在计算中至少使用一个浮点数，这样整个表达式都将升为浮点数：

error[E0502]: cannot borrow `*self` as immutable because it is also borrowed as mutable
  --> src/main.rs:27:30
   |
23 |         let account = self.accounts.get_mut(id).unwrap();
   |                       ------------- mutable borrow occurs here
...
27 |         account.set(balance, self);
   |                 ---          ^^^^ immutable borrow occurs here
   |                 |
   |                 mutable borrow later used by call