SQL 嵌套多选语句

Question

我正在尝试创建一个包含多个嵌套选择语句的嵌套 SQL 语句，用于在 excel vba 中导入记录集。

我想做的是创建类似的东西：

SELECT
    N.LimitN,
    Sum(N.amountN),
    Sum(N1.amountN1)
FROM (
    SELECT year as yearN, Sum(amount) as amountN, limit as limitN
    FROM table1
    WHERE year = 2013
    GROUP BY year, limit) as N
JOIN (
    SELECT year as yearN1, Sum(amount) as amountN1, limit as limitN1
    FROM table1
    WHERE year = 2014
    GROUP BY year, limit) as N1
ON N.LimitN = N1.LimitN1
GROUP BY N.LimitN
ORDER BY N.LimitN;

如果我的原始数据是这样的：

Year       Amount        Limit
2013        100           20
2013         90           30
2013        120           40
2013          5           20
2013        100           30
2013        105           40
2013        150           50
2014        115           20
2014         50           30
2014         95           40
2014        110           50
2014         30           20

我的结果表/记录集将是这样的：

Limit     AmountN (i.e. 2013)   Amount N1 (i.e. 2014)
 20               105                    145
 30               190                     50
 40               225                     95
 50               150                    110

提前致谢

彼得

Answer 1

感觉你的查询有点过于复杂了，你想要的只是amount 的年度总和，按limit 分组。这可以使用CASE 来完成；

SELECT 
  limit, 
  SUM(CASE WHEN year=2013 THEN amount ELSE 0 END) amountN,
  SUM(CASE WHEN year=2014 THEN amount ELSE 0 END) amountN1
FROM myTable
GROUP BY limit
ORDER BY limit;

An SQLfiddle to test with.

（如果我们在这里谈论 Access，您需要使用 IIF 而不是 CASE）