Question

SELECT wavelength, 
           (LEAD(wavelength) OVER (ORDER BY wavelength) - wavelength)/
           (LEAD(reflectance) OVER (ORDER BY wavelength) - reflectance) 
           AS reflectance
    FROM  grassland1

它在Postgresql中显示如下错误

ERROR:  division by zero
********** Error **********

ERROR: division by zero
SQL state: 22012

我将如何纠正这个人有人建议我

Answer 1

使用case然后

SELECT wavelength,
case when (LEAD(reflectance) OVER (ORDER BY wavelength) - reflectance)=0 
     then 0
     else ((LEAD(wavelength) OVER (ORDER BY wavelength) - wavelength)/
          (LEAD(reflectance) OVER (ORDER BY wavelength) - reflectance))
end reflectance
FROM  grassland1

Answer 2

试试这个：

SELECT wavelength, 
       (LEAD(wavelength) OVER (ORDER BY wavelength) - wavelength)/
       (CASE WHEN (LEAD(reflectance) OVER (ORDER BY wavelength) - reflectance) = O THEN 1
        ELSE (LEAD(reflectance) OVER (ORDER BY wavelength) - reflectance) END)
       AS reflectance
FROM  grassland1

Answer 3

这取决于当分母表达式(LEAD(reflectance) OVER (ORDER BY wavelength) - reflectance)的计算结果为0时，您希望如何处理这种情况。假设您希望在计算结果为0时除以1，则可以执行以下操作：

SELECT wavelength, 
           (LEAD(wavelength) OVER (ORDER BY wavelength) - wavelength)/
           (CASE WHEN (LEAD(reflectance) OVER (ORDER BY wavelength) - reflectance) = 0 THEN 1 ELSE (LEAD(reflectance) OVER (ORDER BY wavelength) END)
           AS reflectance
    FROM  grassland1

订购列时PostgreSQL除以零

3 个答案: