如何从mysql中的两个选择的resut中减去

Question

我想减去两个数字，一个是字段的内容，另一个是查询结果的总和，我该怎么办呢？这显示了我想要的，但显然不起作用，该怎么办？

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

Answer 1

尝试这更好的方法是什么：

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

你可以做这样的事情

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实现可以有这样