mysql - postgres 查询不匹配负 double 值

Question

我正在使用 psql (9.1.3)。我有一张 table (比如说)A

A 有两列:

a_id:整数

customer_pay: double

I have these values in the table.

 a_id      | customer_pay |    

--------------------+--------------+

   1733684 |       -264.6 | 
   1723382 |      -314.84 |
   1728106 |        50.55 |
   1741636 |       -264.6 |  (4 rows)

但是当我这么做的时候

select a_id from A where customer_pay = -264.6;

我什么也没有。

我尝试了所有可能的精度变化，例如 -264.60、-264.00 等。 此查询对于 +264.6 准确有效。 我应该如何选择负 double 类型的值。

感谢您的帮助。

Answer 1

select a_id
from a
where round(customer_pay::numeric, 2) = -264.6

From the manual:

Calculations with numeric values yield exact results where possible, e.g. addition, subtraction, multiplication. However, calculations on numeric values are very slow compared to the integer types, or to the floating-point types described in the next section.