在MySQL中獲取每月總費用

Question

我目前正在處理2張桌子，費用和收入。 為了使結構簡單並可以看到它，這是小提琴： http ://sqlfiddle.com/#!9/ 256cd64/2

我需要從查詢中獲得的結果是本年度每個月的總金額，並嘗試了以下操作：

select sum(e.amount) as expense, DATE_FORMAT(e.date,'%m') as month 
from expenses e
where year(e.date) = 2019
group by month

我的問題是，只要他們沒有返回0，那么我只需要花幾個月的時間進行注冊，就算他們沒有注冊也要花12個月。

目前，我正在處理費用表，但我想使用一個查詢來返回每月費用和收入，這是我希望獲得的最終輸出的一個示例：

|   Month | Expense| Incomes |
|---------|--------|---------|
|       01|      0 |       0 |
|       02|   3000 |    4000 |
|       03|   1500 |    5430 |
|       04|  2430  |    2000 |
|       05|  2430  |    1000 |
|       06|  2430  |    1340 |
|       07|     0  |    5500 |
|       08|  2430  |    2000 |
|       09|  1230  |    2000 |
|       10|  8730  |    2000 |
|       11|  2430  |    2000 |
|       12|  6540  |    2000 |

Answer 1

您需要生成月份值，然后使用left join匹配費用：

select coalesce(sum(e.amount), 0) as expense, m.month
from (select '01' as month union all
      select '02' as month union all
      select '03' as month union all
      select '04' as month union all
      select '05' as month union all
      select '06' as month union all
      select '07' as month union all
      select '08' as month union all
      select '09' as month union all
      select '10' as month union all
      select '11' as month union all
      select '12' as month
     ) m left join
     expenses e
     on year(e.date) = 2019 and
        DATE_FORMAT(e.date,'%m') = m.month
group by m.month;

這是db <>小提琴。

至於income ，您應該問另一個問題。

Answer 2

您可以使用MONTH從日期列中獲取月份值，然后使用GROUP BY來獲取所需的輸出，如下所示：

SELECT SUM(e.amount) AS expense, 
MONTH(e.date) AS month    
FROM expenses e
WHERE YEAR(e.date) = 2019
GROUP BY MONTH(e.date)

Answer 3

嘗試將COALESCE(sum(e.amount),0) as expense更改sum(e.amount) as expense ： COALESCE(sum(e.amount),0) as expense

COALESCE函數返回第一個非NULL值。

Answer 4

SELECT
    t1.month,
    COALESCE(t2.amount, 0) AS expenses,
    COALESCE(t3.amount, 0) AS incomes
FROM
(
    SELECT 1 AS month UNION ALL
    SELECT 2 UNION ALL
    SELECT 3 UNION ALL
    SELECT 4 UNION ALL
    SELECT 5 UNION ALL
    SELECT 6 UNION ALL
    SELECT 7 UNION ALL
    SELECT 8 UNION ALL
    SELECT 9 UNION ALL
    SELECT 10 UNION ALL
    SELECT 11 UNION ALL
    SELECT 12
) t1
LEFT JOIN
(
    SELECT MONTH(date) AS month, SUM(amount) AS amount
    FROM expenses
    GROUP BY MONTH(date)
) t2
    ON t1.month = t2.month
LEFT JOIN
(
    SELECT MONTH(date) AS month, SUM(amount) AS amount
    FROM incomes
    GROUP BY MONTH(date)
) t3
    ON t1.month = t3.month
ORDER BY
    t1.month;