Question

我有三张桌子：发票，付款和退款。我希望按类型获得txn计数，按月/年分组。

我正在寻找类似的结果：

Month-Year    Invoices    Payments    Refunds
01-2013        32432        534        32
02-2013        4323        789         53

我可以通过以下方式获得单个表计数（减去一些转换）：

SELECT
    YEAR(txndate)
    , MONTH(txndate)
    , COUNT(*)
    , "Invoice" AS type
FROM invoices
GROUP BY
    YEAR(txndate)
   , MONTH(txndate)

如果归结为它，我可以做三个查询（每个表一个）然后合并我的结果，但我认为必须有一个更聪明的方法。

每个表都有一个TxnDate列。

有什么建议吗？

Answer 1

不确定这是否真的更容易，但你可以用一堆UNION来构建类似的东西：

SELECT year, month, SUM(invoice) AS invoices, SUM(payment) AS payments, SUM(refund) AS refunds
FROM (SELECT YEAR(txndate) AS year, MONTH(txndate) AS month, 
             1 AS invoice, 0 AS payment, 0 AS refund
      FROM   invoices 
      UNION ALL
      SELECT YEAR(txndate) AS year, MONTH(txndate) AS month, 
             0 AS invoice, 1 AS payment, 0 AS refund
      FROM   payments
      UNION ALL
      SELECT YEAR(txndate) AS year, MONTH(txndate) AS month, 
             0 AS invoice, 0 AS payment, 1 AS refund
      FROM   refunds) t
GROUP BY year, month

Answer 2

您可以尝试这样的事情，在

之前添加选择

SELECT

(SELECT COUNT(*)
FROM invoices
WHERE YEAR(txndate) = YEAR(main.txndate) AND MONTH(txndate) = MONTH(main.txndate))
as invoices,

(SELECT COUNT(*)
FROM payments
WHERE YEAR(txndate) = YEAR(main.txndate) AND MONTH(txndate) = MONTH(main.txndate))
as payments,

(SELECT COUNT(*)
FROM refunds
WHERE YEAR(txndate) = YEAR(main.txndate) AND MONTH(txndate) = MONTH(main.txndate))
as refunds

FROM invoices as main
GROUP BY YEAR(txndate), MONTH(txndate)

在一个查询中计算三个表？

2 个答案: