Question

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`

它工作正常，但我需要添加另一个动态字段，它等于rank1 + rank2 ... + rank 5.所以，我要添加另一个字段，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`

它会生成错误“unknown column rank1”。有趣的是，完全相同的查询可以正常使用MS Access。

我该如何解决这个问题？

谢谢！

Answer 1

您不能在同一SELECT语句中使用别名，而是将其放在子查询中，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

Answer 2

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。在您的查询中替换：等级-1 +秩2 + rank3 + rank4 + RANK5 用（5 *（Mean (all) +0.01735568）/（0.07268901））+（5 *（CVaR 95 +0.51612）/（0.53212））.. .. ..

Answer 3

在MySQL中，你不能引用其他别名，但你可以在select中定义变量，所以试试这个：

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，但确实有效。

Answer 4

尝试子查询，例如：

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

MySQL查询中动态生成的字段的总和

4 个答案: