Question

我有这样的四分位数查询：

cast(substring_index(substring_index(group_concat(`lulusanmagisterrangkuman`.`IPK` 
    order by `lulusanmagisterrangkuman`.`IPK` ASC separator ','),',',(((50 / 100) * count(0)) + 1)),',',-(1)) as decimal(10,0)) AS `Median`,
cast(substring_index(substring_index(group_concat(`lulusanmagisterrangkuman`.`IPK` 
    order by `lulusanmagisterrangkuman`.`IPK` ASC separator ','),',',(((25 / 100) * count(0)) + 1)),',',-(1)) as decimal(10,0)) AS `Q1`,
cast(substring_index(substring_index(group_concat(`lulusanmagisterrangkuman`.`IPK` 
    order by `lulusanmagisterrangkuman`.`IPK` ASC separator ','),',',(((75 / 100) * count(0)) + 1)),',',-(1)) as decimal(10,0)) AS `Q3`

但是这个源代码不适用于浮动值。当我尝试这些代码时，返回的值是一个整数。我可以做什么，以便可以在整数或浮点值中看到四分位数？提前致谢

Answer 1

怎么样：您将值转换为decimal(10,0) - 小数的定义精度为10位数，但刻度为零。看看这里：Precision & Scale in MySQL 我在下面的陈述中将它们更改为decimal(18,8)。

此外，您不需要(50 / 100)之类的内容 - 只需使用0.50

cast(substring_index(
        substring_index(
            group_concat(`lulusanmagisterrangkuman`.`IPK` 
                          order by `lulusanmagisterrangkuman`.`IPK` 
                          ASC separator ','
                        ),',',((0.50 * count(0)) + 1)
                       ),',',-(1)
                    ) as decimal(18,8)
    ) AS `Median`,
cast(substring_index(
        substring_index(
            group_concat(`lulusanmagisterrangkuman`.`IPK` 
                          order by `lulusanmagisterrangkuman`.`IPK` 
                          ASC separator ','
                        ),',',((0.25 * count(0)) + 1)
                       ),',',-(1)
                     ) as decimal(18,8)
    ) AS `Q1`,
cast(substring_index(
        substring_index(
            group_concat(`lulusanmagisterrangkuman`.`IPK` 
                          order by `lulusanmagisterrangkuman`.`IPK` 
                          ASC separator ','
                        ),',',((0.75 * count(0)) + 1)
                       ),',',-(1)
                    ) as decimal(18,8)
    ) AS `Q3`

如何在MySQL中查询四分位数1,2和3？

1 个答案: