mysql - 您可以在 MySQL 中的两个别名列上使用数学计算吗？

Question

我想这样做:

SELECT SUM(currentbalance) AS 'current', SUM(principal) AS 'prin', 'current' + 'prin' AS 'total'
FROM dbase

这行不通。我也尝试过:

SELECT sum(currentbalance) AS 'current', sum(principal) AS 'prin', (SELECT 'current') + (SELECT 'prin') AS 'total'
FROM dbase

@juergen-d @fqhv

两个答案都很完美。我认为这足以让我了解如何将其添加到我当前的查询中。我怎样才能在这个查询中实现它？我需要将“file_principal”除以“total_cash_cleared”？提前致谢。

SELECT a.portfolio
       ,a.dateplaced
       ,(SELECT SUM(chargedoffprincipal) FROM Dbase WHERE portfolio = a.portfolio ) AS 'file_principal'
       ,SUM(IF(b.paymentstatus IN ('POSTED','PROCCESED'), paymentamount, 0)) AS 'total_cash_cleared'
       ,SUM(IF(b.paymentstatus = 'PENDING', paymentamount, 0)) AS 'total_cash_pending'
       ,SUM(IF(b.paymentstatus = 'PENDING' AND YEAR(paymentdate) = YEAR(CURRENT_DATE + INTERVAL 1 MONTH) AND MONTH(paymentdate) = MONTH(CURRENT_DATE + INTERVAL 1 MONTH),paymentamount, 0)) AS '30_days'
       ,SUM(IF(b.paymentstatus = 'PENDING' AND YEAR(paymentdate) = YEAR(CURRENT_DATE + INTERVAL 1 MONTH) AND MONTH(paymentdate) = MONTH(CURRENT_DATE + INTERVAL 2 MONTH),paymentamount, 0)) AS '60_days'
       ,SUM(IF(b.paymentstatus = 'PENDING' AND YEAR(paymentdate) = YEAR(CURRENT_DATE + INTERVAL 1 MONTH) AND MONTH(paymentdate) = MONTH(CURRENT_DATE + INTERVAL 3 MONTH),paymentamount, 0)) AS '90_days'
FROM dbase a
LEFT JOIN payments b
ON a.filenumber = b.filenumber
GROUP BY a.portfolio
ORDER BY STR_TO_DATE(a.dateplaced, '%m/%d/%Y') DESC

我尝试在评论中添加此内容，但它太长了，所以我编辑了这篇文章，抱歉。

Answer 1

不能在同一 SELECT 子句中重复使用别名

SELECT SUM(currentbalance) AS 'current', 
       SUM(principal) AS 'prin', 
       SUM(currentbalance + principal) AS 'total'
FROM dbase