mySQL 查询，用于对列(月)中的金额求和

Question

>我有以下格式的数据：

date（月/日/年）、desc（明细）、category（a、b、c）、tran_type（借方、贷方）、amount spent（金额）。

我想以以下格式获取数据：

category  ||  tran_type   ||   Jan_total  ||  feb_total  ||  mar_total  
A         ||  debit       ||   $101       ||  $201       ||  $302  
A         ||  credit      ||   $500       ||  $600       ||  $200  

Answer 1

此查询应提供所需的结果。

SELECT category
  ,tran_type
  ,SUM(IF(month(date) = 1,ABS(amount),0)) as jan_total
  ,SUM(IF(month(date) = 2,ABS(amount),0)) as feb_total
  ,SUM(IF(month(date) = 3,ABS(amount),0)) as mar_total
  ,SUM(IF(month(date) = 4,ABS(amount),0)) as apr_total
  ,SUM(IF(month(date) = 5,ABS(amount),0)) as may_total
  ,SUM(IF(month(date) = 6,ABS(amount),0)) as jun_total
  ,SUM(IF(month(date) = 7,ABS(amount),0)) as jul_total
  ,SUM(IF(month(date) = 8,ABS(amount),0)) as aug_total
  ,SUM(IF(month(date) = 9,ABS(amount),0)) as sep_total
  ,SUM(IF(month(date) = 10,ABS(amount),0)) as okt_total
  ,SUM(IF(month(date) = 11,ABS(amount),0)) as nov_total
  ,SUM(IF(month(date) = 12,ABS(amount),0)) as dec_total
 FROM transactions
 WHERE YEAR(date) = '2011'
 GROUP BY category, tran_type

如果您不想遇到麻烦，请不要忘记按年份过滤。

Answer 2

那么年份呢？是否希望 1 月列添加 2011 年 1 月与 2010 年 1 月的交易记录？

我假设您需要单独添加年份列或使用 WHERE 子句，因此在示例中包括了两个选项：

基本上，您需要生成十二个子查询才能实现这一点，并且SQL看起来很混乱，并且不是完成此操作的常规方法：

SELECT category, YEAR(date), tran_type,
    (SELECT SUM(amounts) FROM TableName s1 WHERE YEAR(t.date)=YEAR(s1.date) AND MONTH(s1.date)=1 AND t.category=s1.category AND t.tran_type=s1.tran_type) AS 'Jan_Total',
    (SELECT SUM(amounts) FROM TableName s2 WHERE YEAR(t.date)=YEAR(s2.date) AND MONTH(s2.date)=2 AND t.category=s2.category AND t.tran_type=s2.tran_type) AS 'Feb_Total',
     ....REPEAT ABOVE 2 LINES FOR EACH MONTH
FROM TableName t
WHERE t.date>'2011-01-01'
GROUP BY t.category, YEAR(t.date), t.tran_type;

如前所述，上面并不完全优雅，更好的解决方案是使用以下 SQL 并将表示层中的数据格式化给用户：

SELECT category, YEAR(date), MONTH(date), tran_type, SUM(amounts)
FROM TableName
GROUP BY TableName;

希望有帮助。

Answer 3

对于单个月（2011 年 1 月），您可以使用：

SELECT category, tran_type, SUM(amount_spent) AS total FROM myTable WHERE date>="2011-01-01" AND date<"2011-02-01" GROUP BY category, tran_type;

假设您至少有一个索引 date那么这应该相当快。(date, category, tran_type)更好的索引，因为这也有助于分组。

如果要以所描述的格式组合多个月份，可以将这些查询中的许多组合为子查询，如下所示：

SELECT jan.category, jan.tran_type, jan.total, feb.total FROM
    (SELECT category, tran_type, SUM(amount_spent) AS total FROM myTable WHERE date>="2011-01-01" AND date<"2011-02-01" GROUP BY category, tran_type) AS jan,
    (SELECT category, tran_type, SUM(amount_spent) AS total FROM myTable WHERE date>="2011-02-01" AND date<"2011-03-01" GROUP BY category, tran_type) AS feb
 WHERE jan.category = feb.category
 AND jan.tran_type = feb.tran_type;

虽然我怀疑获取所需数据的最简单方法（尽管效率不高，格式也不完全符合您描述的格式）是：

SELECT category, tran_type, MONTH(date) AS theMonth, SUM(amount_spent) AS total FROM myTable WHERE date>="2011-01-01" AND date<"2012-01-01" GROUP BY category, tran_type, theMonth;

MONTH()函数的这种使用远非最佳选择，但如果您不运行查询，这通常是要走的路。