连接数据集的 SQL 计算

Question

我是 SQL 新手，我一直在研究一个数据集，我想在其中加入两个数据集并计算它们的方差：

SELECT 
    dataset_1.column_1,
    SUM(dataset_1.column2) AS column_2,
    SUM(dataset_2.column3) AS column3,
    column_2 - column_3 AS Variance
FROM 
    source_data.dataset1 AS dataset_1
JOIN
    source_data.dataset2 AS dataset_2
    ON dataset_1.column_1 = dataset_2.column_1
GROUP BY 
    dataset_1.column_1
ORDER BY
    dataset_1.column_1

行中有错误：

 column_2 - column_3 AS Variance

说它不识别 column_2。 如何解决显示另一列差异？

Answer 1

SELECT 
    dataset_1.column_1,
    SUM(dataset_1.column2) AS column_2,
    SUM(dataset_2.column3) AS column3,
    SUM(dataset_1.column2) - SUM(dataset_2.column3 AS Variance
FROM 
    source_data.dataset1 AS dataset_1
JOIN
    source_data.dataset2 AS dataset_2
    ON dataset_1.column_1 = dataset_2.column_1
GROUP BY 
    dataset_1.column_1
ORDER BY
    dataset_1.column_1

令人讨厌的是，您不能在 select 语句中使用别名进行计算。