在单个表上的多个时间间隔上应用乘法

Question

我的数据由1024行和2列组成。它的结构类似于

  

我想根据第一列从单个表中选择三个区间。在选定的时间间隔内，第二列值应乘以值

SELECT * FROM del 
   WHERE wavelength BETWEEN 341 AND 348 
         OR wavelength BETWEEN 551 AND 664  
         OR wavelength BETWEEN 998 AND 1021

在这一个中，使用此查询和

选择间隔

• 第一个间隔第二列值乘以0.25
• 第二个间隔第二列乘以0.5
• 第三个间隔第二列应乘以0.25。

在乘法后，我想在第二列中显示波长和相乘的反射率值

Answer 1

试试这个：

SELECT wavelength, 
       CASE WHEN wavelength BETWEEN 551 AND 664 THEN reflectance * .5
            ELSE  reflectance * .25 
       END AS 'REFLECTANCE'
FROM del 
WHERE wavelength BETWEEN 341 AND 348 
   OR wavelength BETWEEN 551 AND 664  
   OR wavelength BETWEEN 998 AND 1021

或常见的选择：

SELECT wavelength, 
       CASE WHEN (wavelength BETWEEN 341 AND 348) 
              OR (wavelength BETWEEN 998 AND 1021) THEN reflectance * .25 
            WHEN wavelength BETWEEN 551 AND 664 THEN reflectance * .5
            ELSE 1 ---(PUT YOUR DEFAULT) 
       END AS 'REFLECTANCE'
FROM del

Answer 2

第一个和第三个范围乘以0.25，第二个范围乘以0.5

您可以使用以下查询。

SELECT wavelength, 
       ( reflect * 0.25 ) AS reflect 
FROM   wavelength 
WHERE  ( wavelength BETWEEN 341 AND 348 ) 
        OR ( wavelength BETWEEN 998 AND 1021 ) 
UNION ALL 
SELECT wavelength, 
       ( reflect * 0.5 ) AS reflect 
FROM   wavelength 
WHERE  wavelength BETWEEN 551 AND 664; 

如果要将所有三个乘以不同的值，则可以使用

SELECT wavelength, 
       ( reflect * 0.25 ) AS reflect 
FROM   wavelength 
WHERE  wavelength BETWEEN 341 AND 348 
       OR wavelength BETWEEN 998 AND 1021 
UNION ALL 
SELECT wavelength, 
       ( reflect * 0.5 ) AS reflect 
FROM   wavelength 
WHERE  wavelength BETWEEN 551 AND 664 
UNION ALL 
SELECT wavelength, 
       ( reflect * 0.25 ) AS reflect 
FROM   wavelength 
WHERE  wavelength BETWEEN 998 AND 1021 

演示http://sqlfiddle.com/#!2/2c41b/10