如何從mysql中的兩個選擇的resut中減去

Question

我想減去兩個數字，一個是字段的內容，另一個是查詢結果的總和，我該怎麼辦呢？這顯示了我想要的，但顯然不起作用，該怎麼辦？

SELECT monto FROM programaPago WHERE id=2 
**MINUS** 
SELECT SUM(caja.monto) FROM caja WHERE caja.programaPago_id =2 

Answer 1

嘗試這更好的方法是什麼：

SELECT (programaPago.monto - COALESCE(iTotal.TotalMonto,0)) Result 
FROM programaPago LEFT JOIN 
    (SELECT programaPago_id, SUM(monto) as TotalMonto 
    FROM caja GROUP BY programaPago_id) as iTotal 
     ON programaPago.ID = iTotal.programaPago_id 
WHERE programaPago.ID = 2 

Answer 2

你可以做這樣的事情

SELECT 
    (SELECT monto FROM programaPago WHERE id = 2) - 
    (SELECT SUM(caja.monto) FROM caja WHERE caja.programaPago_id = 2) 

但不知道你正在努力實現可以有這樣