比较同一列中的数据-SQL

Question

在比较同一列中的数据时，我需要帮助。例如我有一个包含ID，名称，地址，城市，州和星星列的业务表。

“星星”列包含以下值：1.0、1.5、2.0、2.5、3.0、3.5、4.0、4.5、5.0。

现在我必须将2-3星的企业与4-5星的企业进行比较，那么我该怎么做？任何帮助表示赞赏。

谢谢。

Answer 1

我猜“他们”想要每颗恒星数。
如果是这样，那么您可以在一个CASE上分组。

SELECT 
(CASE 
 WHEN stars BETWEEN 0.0 AND 1.5 THEN '0.0-1.5'
 WHEN stars BETWEEN 2.0 AND 3.5 THEN '2.0-3.5'
 WHEN stars BETWEEN 4.0 AND 5.0 THEN '4.0-5.0'
 END) as stars_range,
COUNT(*) AS TotalBusiness,
COUNT(DISTINCT city) AS TotalCities,
COUNT(DISTINCT state) AS TotalStates
FROM Business
WHERE stars BETWEEN 2.0 AND 5.0
GROUP BY 
(CASE 
 WHEN stars BETWEEN 0.0 AND 1.5 THEN '0.0-1.5'
 WHEN stars BETWEEN 2.0 AND 3.5 THEN '2.0-3.5'
 WHEN stars BETWEEN 4.0 AND 5.0 THEN '4.0-5.0'
 END)

还是有条件的聚合看起来更好？

SELECT 
COUNT(CASE WHEN stars BETWEEN 2.0 AND 3.5 THEN 1 END) AS stars_2_3,
COUNT(CASE WHEN stars BETWEEN 4.0 AND 5.0 THEN 1 END) AS stars_4_5
FROM Business
WHERE stars BETWEEN 2.0 AND 5.0