MySQL查询中动态生成字段的总和

这是我对动态计算字段的查询：

SELECT 5 * (`Mean (all)` +0.01735568 )/(0.07268901) AS rank1, 
5 * (`CVaR 95` +0.51612 )/(0.53212) AS rank2, 
5 * (`Hurst` - 0.2 )/(0.7717653) AS rank3, 
5 * (`MaxDD` +6.200000762939453 )/(16.200000762939) AS rank4, 
5 * (`Positive % 12` - 0.3 )/(1) AS rank5
FROM `quant1`

它工作得很好，但我需要添加另一个动态字段，它等于rank1+rank2…+rank5。因此，我添加了另一个字段，如

SELECT 5 * (`Mean (all)` +0.01735568 )/(0.07268901) AS rank1, 
5 * (`CVaR 95` +0.51612 )/(0.53212) AS rank2, 
5 * (`Hurst` - 0.2 )/(0.7717653) AS rank3, 
5 * (`MaxDD` +6.200000762939453 )/(16.200000762939) AS rank4, 
5 * (`Positive % 12` - 0.3 )/(1) AS rank5,
rank1+rank2+rank3+rank4+rank5 AS rank
FROM `quant1`

它生成一个错误“未知列rank1”。有趣的是，完全相同的查询在MS Access中运行良好

我怎样才能解决这个问题

---

谢谢

不能在同一

SELECT

语句中使用别名，请将其放在子查询中，如下所示：

SELECT rank1, rank2, rank3, rank4, rank5,
  rank1 + rank2 + rank3 + rank4 + rank5 AS rank
FROM
(

    SELECT 5 * (`Mean (all)` +0.01735568 )/(0.07268901) AS rank1, 
    5 * (`CVaR 95` +0.51612 )/(0.53212) AS rank2, 
    5 * (`Hurst` - 0.2 )/(0.7717653) AS rank3, 
    5 * (`MaxDD` +6.200000762939453 )/(16.200000762939) AS rank4, 
    5 * (`Positive % 12` - 0.3 )/(1) AS rank5
    FROM `quant1`
) AS t

你必须有办法。 1.将这些查询用作子查询：

select R.*,R.rank1+R.rank2+R.rank3+R.rank4+R.rank5 AS rank from (
SELECT 5 * (`Mean (all)` +0.01735568 )/(0.07268901) AS rank1, 
5 * (`CVaR 95` +0.51612 )/(0.53212) AS rank2, 
5 * (`Hurst` - 0.2 )/(0.7717653) AS rank3, 
5 * (`MaxDD` +6.200000762939453 )/(16.200000762939) AS rank4, 
5 * (`Positive % 12` - 0.3 )/(1) AS rank5
FROM `quant1`
) as R

或 2. 在查询中，请替换： rank1+rank2+rank3+rank4+rank5 使用（5*（

Mean（all）

+0.01735568）/（0.07268901））+（5*（

cvar95

+0.51612）/（0.53212））等尝试子查询，如：

SELECT *, rank1+rank2+rank3+rank4+rank5 AS rank 
FROM (   
  SELECT 5 * (`Mean (all)` +0.01735568 )/(0.07268901) AS rank1, 
  5 * (`CVaR 95` +0.51612 )/(0.53212) AS rank2, 
  5 * (`Hurst` - 0.2 )/(0.7717653) AS rank3, 
  5 * (`MaxDD` +6.200000762939453 )/(16.200000762939) AS rank4, 
  5 * (`Positive % 12` - 0.3 )/(1) AS rank5,
  FROM `quant1`
)  QuantRank

---

在MySQL中，您不能引用其他别名，但可以在select中定义变量，因此请尝试以下方法：

SELECT
   @rank1 := 5 * (`Mean (all)` +0.01735568 )/(0.07268901) AS rank1, 
   @rank2 := 5 * (`CVaR 95` +0.51612 )/(0.53212) AS rank2, 
   @rank3 := 5 * (`Hurst` - 0.2 )/(0.7717653) AS rank3, 
   @rank4 := 5 * (`MaxDD` +6.200000762939453 )/(16.200000762939) AS rank4, 
   @rank5 := 5 * (`Positive % 12` - 0.3 )/(1) AS rank5,
   @rank1 + @rank2 + @rank3 + @rank4 + @rank5 AS rank
FROM `quant1`

---

这很难看，但很管用。

就我个人而言，我不推荐选项2——它们会很快失去同步。使用子查询可能是唯一的方法。选项1生成一个错误：“错误代码：1248每个派生表都必须有自己的别名”。你需要在末尾加上“AS someTable”它可以工作。。。10000行的执行时间为0.062秒，比下面Mats Kindahl的解决方案略差。请注意，子查询在历史上对优化器并不好。它在最新的MySQL版本中有所改进，但它确实推动了优化器的发展。